Physics Final
If a vector has components Ax < 0, and Ay < 0, then the angle that this vector makes with the positive x-axis must be in the range
0 - 90 *
The following exact conversion equivalents are given: 1 m = 100 cm , 1 in = 2.54 cm, and If a computer screen has an area of 1.27 ft2, this area is closest to
0.118 m2
A bicyclist starts a timed race at In order to win, he must average Assuming constant acceleration from the start, how fast must he be traveling at the end of the race?
36 mi/h
An object is moving in a straight line with constant acceleration. Initially it is traveling at 16 m/s. Three seconds later it is traveling at 10 m/s. How far does it move during this time?
39 m
The number 0.003010 has
4 significant figures.
A boy kicks a football with an initial velocity of 20 m/s at an angle of 25° above the horizontal. If we neglect air resistance, the magnitude of the acceleration of the ball while it is in flight is
9.8 m/s2
As shown in the figure, a 60-cm length of uniform wire, of mass 60 g, is bent into a right triangle. What are the x and y coordinates of the center of mass (or center of gravity) of this triangle?
(10 cm, 3.0 cm)
What is the sum of 1123 and 10.3 written with the correct number of significant figures?
1133
A plot of land contains How many square meters does it contain?
2.3x104 m2
A car travels 20 km west and then 20 km south. What is the magnitude of its displacement vector?
28 km
Express a body temperature 98.6°F in Celsius degrees.
37.0 °C
Ideal incompressible fluid flows through a 4.0-cm-diameter pipe at 1.0 m/s. There is a 2.0 cm diameter constriction in the line. What is the speed of the fluid in this constriction?
4 m/s
An ideal gas has a pressure of 2.5 atm, a volume of 1.0 L at a temperature of 30°C. How many molecules are there in this gas? (R = 8.31 J/mol K,1.00 atm = 101 kPa, NA = 6.022 × 1023)
6.0 × 1022
The mass of a typical adult woman is closest to
65 kg
If you run a complete loop around an outdoor track of length 400 m in 100 s, find your (a) average velocity and (b) average speed.
Both are 4.00
Two small balls, A and B, attract each other gravitationally with a force of magnitude F. If we now double both masses and the separation of the balls, what will now be the magnitude of the attractive force on each one?
F
While flying horizontally in an airplane, you notice that a string dangling from the overhead luggage compartment hangs at rest at 15° away from the vertical toward the front of the plane. Using this observation, you can conclude that the airplane is
accelerating backward.
A 25-kg piece of equipment can be hung by steel wires of length 1.00 m, 2.00 m, or 3.00 m. If all the wires have the same diameter, which one will stretch the greatest distance?
the 3.00-m wire
The center of mass (or center of gravity) of a two-particle system is at the origin. One particle is located at (3.0 m, 0.0 m) and has a mass of 2.0 kg. The other particle has a mass of 3.0 kg. What is the location of the 3.0-kg particle?
(-2.0m, 0.0m)
marble moving 1.48 m/s rolls off the top edge of a 125-cm high table in a room where there is no appreciable air resistance and the acceleration due to gravity is 9.80 m/s2. (a) How far from the base of the table will it strike the floor? (b) How long will it be in the air?
(a) 1.36 m (b) 0.151 s
A crane lifts a steel submarine of density 7800 kg/m3 and mass 20,000 kg. What is the tension in the lifting cable (a) when the submarine is submerged in water of density 1000 kg/m3, and (b) when it is entirely out of the water?
(a) 1.7 × 105 N (b) 2.0 × 105 N
A car that is initially moving at 7.50 m/s begins to accelerate forward uniformly at 0.550 m/s2 (a) How long after beginning to accelerate does it take the car to move 3.50 km? (b) How fast is the car moving just as it has traveled 3.50 km?
(a) 100s (b) 62.5 m/s
You are the science officer on a visit to a distant solar system. Prior to landing on a planet you measure its diameter to be 1.8 × 107 m. You have previously determined that the planet orbits 2.9 × 1011 m from its star with a period of 402 earth days. Once on the surface you find that the acceleration due to gravity is 19.5 m/s2. What are the masses of (a) the planet and (b) the star? (G = 6.67 × 10-11 N m2/kg2)
(a) 2.4 kg × 1025 kg (b) 1.2 kg × 1031 kg
A ball is thrown straight up with a speed of 30 m/s, and air resistance is negligible(a) How long does it take the ball to reach the maximum height? (b) What is the maximum height reached by the ball?(c) What is its speed after 4.2 s?
(a) 3.1s (b) 46m (c) -11
An auto accelerates forward from 7.0 m/s at a uniform 0.71 m/s2. It travels a distance of 1.033 km while accelerating. (a) How fast is the auto moving just as it is traveled the 1.033 km?(b) How many seconds did it take to travel the 1.033 km?
(a) 38.38m/s (b) 44.20s
Which of the following quantities has units of a velocity? (There could be more than one correct choice.)
-120 m/s AND 9.8 m/s downward
The weather outside is frightful. The temperature is -22°F. What is the corresponding temperature in the Celsius scale?
-30 C
A person carries a 2.00-N pebble through the path shown in the figure, starting at point A and ending at point B. The total time from A to B is 6.75 min. How much work did gravity do on the rock between A and B?
-30.0 J
A ball is projected upward at time t = 0 s, from a point on a flat roof 10 m above the ground. The ball rises and then falls with insignificant air resistance, missing the roof, and strikes the ground. The initial velocity of the ball is Consider all quantities as positive in the upward direction. At time the vertical velocity of the ball is closest to
0 m/s
In a laboratory experiment, a student brings up the rotational speed of a flywheel to 30.0 rpm. She then allows it to slow down on its own, and counts 240 revolutions before the apparatus uniformly comes to a stop. The moment of inertia of the flywheel is 0.0850 kg m2. What is the magnitude of the retarding torque on the flywheel?
0.000278 N m
A fluid is flowing with an average speed of 1.5 m/s through a tube that has a radius of 2.0 mm and is 18 cm long. The drop in pressure is 967 Pa. What is the viscosity of the fluid?
0.0018 N s/m2
Two air track carts move along an air track towards each other. Cart A has a mass of 450 g and moves toward the right with a speed of 0.850 m/s. Cart B has a mass of 300 g and moves toward the left with a speed of 1.12 m/s. What is the total momentum of the two-cart system?
0.047 kg m/s toward the right
An object slides on a level floor. It slows and comes to a stop with a constant acceleration of magnitude 2.4 m/s2. What is the coefficient of kinetic friction between the object and the floor?
0.24
What buoyant force does a 0.60-kg solid gold crown experience when it is immersed in water? The density of gold is 19.3 × 103 kg/m3 and that of water is 1000 kg/m3.
0.3 N
A car is traveling north at After 12 s its velocity is in the same direction. Find the magnitude and direction of the car's average acceleration.
0.30 m/s2, south
A 50.0-kg block is being pulled up a 16.0° slope by a force of 250 N that is parallel to the slope. The coefficient of kinetic friction between the block and the slope is 0.200. What is the acceleration of the block?
0.412 m/s2
If NASA wants to put a satellite in a circular orbit around the sun so it will make 2.0 orbits per year, at what distance (in astronomical units, AU) from the sun should that satellite orbit? The earth's orbit is 1.0 AU from the sun.
0.50 AU
A 1.0-kg object moving in a certain direction has a kinetic energy of 2.0 J. It hits a wall and comes back with half its original speed. What is the kinetic energy of this object at this point?
0.50 J
A brass wire 2.0 m long and 2.0 mm in diameter supports a 10.0-kg fixture. By what distance did this fixture stretch the wire? Young's modulus for brass is 10 × 1010 N/m2.
0.62
A rolling wheel of diameter of 68 cm slows down uniformly from 8.4 m/s to rest over a distance of 115 m. What is the magnitude of its angular acceleration if there was no slipping?
0.90
An aluminum rod is 10.0 cm long and a steel rod is 80.0 cm long when both rods are at a temperature of 15°C. Both rods have the same diameter. The rods are now joined end-to-end to form a rod 90.0 cm long. If the temperature is now raised from 15°C to 90°C, what is the increase in the length of the joined rod? The coefficient of linear expansion of aluminum is 2.4 × 10-5 K-1 and that of steel is 1.2 × 10-5 K-1.
0.90 mm
Which two temperature changes are equivalent?
1 C° = 1 K
If Earth had twice its present mass but it orbited at the same distance from the sun as it does now, its orbital period would be
1 year
The horizontal and vertical components of the initial velocity of a football are 16 m/s and 20 m/s respectively. If there is no air resistance, how long does it take the football to reach the top of its trajectory?
1.0 s
A solid wood door, 90.0 cm wide by 2.00 m tall has a mass of 35.0 kg. It is open and at rest. A small 500-g ball is thrown perpendicular to the door with a speed of 20.0 m/s and hits the door 60.0 cm from the hinged side. The ball rebounds with a speed of 16.0 m/s along the same line. What is the angular speed of the door just after the collision with the ball?
1.14 rad/sec
In another solar system, a planet has an airless moon Zygo that is 4.0 × 105 m in diameter. Experiments reveal that a freely falling object at the surface of Zygo accelerates at 0.20 m/s2. What is the mass of Zygo? (G = 6.67 × 10-11 N m2/kg2)
1.2 × 1020 kg
A 120-kg refrigerator that is 2.0 m tall and 85 cm wide has its center of mass at its geometrical center. You are attempting to slide it along the floor by pushing horizontally on the side of the refrigerator. The coefficient of static friction between the floor and the refrigerator is 0.30. Depending on where you push, the refrigerator may start to tip over before it starts to slide along the floor. What is the highest distance above the floor that you can push the refrigerator so that it will not tip before it begins to slide?
1.4
A 100-g ball falls from a window that is 12 m above ground level and experiences no significant air resistance as it falls. What is its momentum when it strikes the ground?
1.5 kg x m/s
In a police ballistics test, a 10.0-g bullet moving at 300 m/s is fired into a 1.00-kg block at rest. The bullet goes through the block almost instantaneously and emerges with 50.0% of its original speed. What is the speed of the block just after the bullet emerges?
1.50 m/s
Opposing shearing forces of 3000 N are applied to the 4.00-cm × 5.00-cm faces of a metal block measuring 3.00 cm × 4.00 cm × 5.00 cm. By what amount does the block become slanted? The shear modulus for this metal is 8.10 × 1010 N/m2.
1.54 × 10-6 m
Heat is added to a 3.0 kg piece of ice at a rate of How long will it take for the ice at 0.0° C to melt? For water LF = 334,000 J/kg and LV = 2.246 × 106 J/kg.
1.6 sec
Calculate the average force a bumper would have to exert to bring a 1200-kg car to rest in 15 cm when the car had an initial speed of 2.0 m/s (about 4.5 mph).
1.6 x 10 4 N
Calculate the average force a bumper would have to exert to bring a 1200-kg car to rest in 15 cm when the car had an initial speed of 2.0 m/s (about 4.5 mph).
1.6 × 104 N
A 0.140-kg baseball is dropped from rest from a height of 2.20 m above the ground and experiences negligible air resistance as it falls. It rebounds to a height of 1.60 m. What change in the ball's momentum occurs as it rebounds from the ground?
1.70 kg m/s upwards
A potter's wheel has the shape of a solid uniform disk of mass and radius 0.65 m. It spins about an axis perpendicular to the disk at its center. A small 2.1 kg lump of very dense clay is dropped onto the wheel at a distance 0.41 m from the axis. What is the moment of inertia of the system about the axis of spin?
1.8 kg m2
Consider two equal-volume flasks of gas at the same temperature and pressure. One gas, oxygen, has a molecular mass of 32. The other gas, nitrogen, has a molecular mass of 28. What is the ratio of the number of oxygen molecules to the number of nitrogen molecules in these flasks?
1/1
Suppose our sun had 4 times its present mass but the earth orbited it at the same distance as it presently does. What would be the length of the year on the earth under those conditions?
1/2 as long as the present year
The acceleration due to gravity on Planet A is one-sixth what it is on Planet B, and the radius of the Planet A is one-fourth that of Planet B. The mass of Planet A is what fraction of the mass of Planet B?
1/96
A 2.0-kg ball moving eastward at 3.0 m/s suddenly collides with and sticks to a 4.0-kg ball moving northward at 2.0 m/s. What is the magnitude of the momentum of this system just after the collision?
10 kg m/s
A boat, whose speed in still water is 8.0 m/s, crosses a river with a current of 6.0 m/s. If the boat heads perpendicular to the current, what is the speed of the boat relative to an observer standing on the shore as it crosses the river?
10 m/s
A heat-conducting rod, 0.90 m long and wrapped in insulation, is made of an aluminum section that is 0.20 m long and a copper section that is long. Both sections have a cross-sectional area of The aluminum end and the copper end are maintained at temperatures of and respectively. The thermal conductivities of aluminum and copper are 205 W/m K (aluminum) and 385 W/m K (copper). What is the temperature of the aluminum-copper junction in the rod with steady state heat flow?
100 C
An athlete holds a 7.5-kg shot put in his hand with his lower arm horizontal, as shown in the figure. His lower arm has a mass of 2.8 kg and its center of gravity (or center of mass) is 12 cm from the elbow-joint pivot. How much force must the extensor muscle (which is M in the figure) in the upper arm exert on the lower arm?
1000 N
Three solid, uniform, cylindrical flywheels, each of mass 65.0 kg and radius 1.47 m, rotate independently around a common axis through their centers. Two of the flywheels rotate in one direction at 8.94 rad/s, but the other one rotates in the opposite direction at 3.42 rad/s. Calculate the magnitude of the net angular momentum of the system.
1020 kg m2/s
Originally 2.00 mol of gas are at STP. If the temperature changes to 47.0°C and the pressure decreases to half of what it was, how many liters do the two moles now occupy? (1 atm = 101 kPa, R = 8.31 J/mol K)
105 L
A particularly scary roller coaster contains a loop-the-loop in which the car and rider are completely upside down. If the radius of the loop is with what minimum speed must the car traverse the loop so that the rider does not fall out while upside down at the top? Assume the rider is not strapped to the car.
11.4 m/s
A bat, flying toward the east at 2.0 m/s, emits a shriek that is reflected back to it from a wall that is 20.0 m in front of the bat at the instant the shriek is emitted. Sound travels at 340 m/s in the air. How many milliseconds after emitting the shriek does the bat hear the reflected echo from the wall?
117 ms
A steel wire, 3.2 m long, has a diameter of 1.2 mm. The wire stretches 1.6 mm when it bears a load. Young's modulus for steel is 2.0 × 1011 Pa. The mass of the load is closest to
12 kg
An aluminum electric tea kettle with a mass of 500 g is heated with a 500-W heating coil. How long will it take to heat up 1.0 kg of water from 18°C to 98°C in the tea kettle? The specific heat of aluminum is 900 J/kg K and that of water is 4186 J/kg K.
12 minutes
The planet Jupiter is 7.78 × 1011 m from the sun. How long does it take for Jupiter to orbit once about the sun given that the distance from the earth to the sun is 1.50 × 1011 m?
12 years
An astronaut stands by the rim of a crater on the Moon, where the acceleration of gravity is 1.62 m/s2 and there is no air. To determine the depth of the crater, she drops a rock and measures the time it takes for it to hit the bottom. If the depth of the crater is 120 m, how long does it take for the rock to fall to the bottom of the crater?
12.2
A glass flask has a volume of 500 mL at a temperature of 20° C. The flask contains 492 mL of mercury at an equilibrium temperature of 20°C. The temperature is raised until the mercury reaches the 500 mL reference mark. At what temperature does this occur? The coefficients of volume expansion of mercury and glass are 18 ×10-5 K-1 (mercury) and 2.0 ×10-5 K-1 (glass).
120 C
When a container of water is placed on a laboratory scale, the scale reads 120 g. Now a 20-g piece of copper (of density 8.9 g/cm3) is suspended from a thread and lowered into the water, not touching the bottom of the container. What will the scale now read? The density of water is 1.0 g/cm3.
122g
Object 1 has three times the specific heat capacity and four times the mass of Object 2. The two objects are given the same amount of heat. If the temperature of Object 1 changes by an amount T, the change in temperature of Object 2 will be
12ΔT
The components of vectors and are given as follows: What is the magnitude of the vector difference - ?
13
A pencil that is 15.7 cm long is released from a vertical position with the eraser end resting on a table. The eraser does not slip as it tips over. Treat the pencil like a uniform rod. What is the angular speed of the pencil just before it hits the table?
13.7
A projectile is fired from ground level with a speed of 150 m/s at an angle 30° above the horizontal on an airless planet where g = 10.0 m/s2. What is the horizontal component of its velocity after 4.0 s?
130 m/s
Starting from rest, a dragster travels a straight 1/4 mi racetrack in 6.70 s with constant acceleration. What is its velocity when it crosses the finish line?
135 mi/h
Water flows out of a large reservoir through an open pipe, as shown in the figure. What is the speed of the water as it comes out of the pipe?
13m/s
A car heading north suddenly collides at an intersection with a truck of the same mass heading east. If they lock together and travel at at 15° north of east just after the collision, how fast was the car initially traveling?
14 m/s
A stepladder consists of two halves that are hinged at the top and connected by a tie rod which keeps the two halves from spreading apart. In this particular instance, the two halves are 2.5 m long, the tie rod is connected to the center of each half and is 70 cm long. An 800-N person stands 3/5 of the way up the stepladder, as shown in the figure. The ladder is light enough that we can neglect its weight, and it rests on an extremely smooth floor. What is the tension in the tie rod? (Note: To solve this problem, it is helpful to imagine cutting the ladder in half vertically and consider the forces and torques acting on each half of the ladder.)
140 N
A lab student drops a 400.0-g piece of metal at 120.0°C into a cup containing 450.0 g of water at 15.0°C. After waiting for a few minutes, the student measures that the final temperature of the system is 40.0°C. What is the specific heat of the metal, assuming that no significant heat is exchanged with the surroundings or the cup? The specific heat of water is 4186 J/kg K.
1470
A racquetball strikes a wall with a speed of 30 m/s and rebounds in the opposite direction with a speed of 26 m/s. The collision takes 20 ms. What is the average acceleration of the ball during the collision with the wall?
1500 m/s2
A rock is projected upward from the surface of the Moon, at time t = 0 s, with an upward velocity of 30.0 m/s. The acceleration due to gravity at the surface of the Moon is 1.62 m/s2, and the Moon has no atmosphere. The height of the rock when it is descending with a speed of 20.0 m/s is closest to
154 m
How many nanoseconds does it take for a computer to perform one calculation if it performs calculations per second?
15ns
A 25-kg television set rests on four rubber pads that are on the floor, each one having a height of 1.0 cm and a radius of 0.60 cm. A horizontal force is applied to the television set. When the pads are just at the point of sliding over the floor, how far has the television set moved sideways due to the deformation of the pads? The coefficient of static friction between the rubber and the floor is 1.0 and the shear modulus of these rubber pads is 2.6 × 106 Pa.
16
The figure shows four vectors, , having magnitudes 12.0 m, 10.0 m, 8.0 m, and 4.0 m, respectively. The sum of these four vectors is
16.4 m at an angle 77.8° with respect to +x-axis.
A 200-N sled of slides down a frictionless hillside that rises at 37° above the horizontal. What is the magnitude of the force that the surface of the hill exerts on the sled?
160 N
An object having a fixed emissivity of 0.725 radiates heat at a rate of 10 W when it is at an absolute temperature T. If its temperature is doubled to 2T, at what rate will it now radiate?
160 W
A jogger is running outdoors on a cold day when the temperature is -20.0°C. She is breathing at the rate of 25 breaths per minute, and each time she breathes in she inhales 0.00450 m3 of air. How much heat does she lose from breathing during 20.0 minutes of jogging if the air in her lungs is heated to her body temperature of 37.0°C before it is exhaled? The specific heat of air is 1020 J/kg K and the density of air under typical conditions is 1.29 kg/m3.
169
A 360-g metal container, insulated on the outside, holds 180.0 g of water in thermal equilibrium at 22.0°C. A 24.0-g ice cube, at the melting point, is dropped into the water, and when thermal equilibrium is reached the temperature is 15.0°C. Assume there is no heat exchange with the surroundings. For water, the specific heat capacity is 4190 J/kg K and the heat of fusion is 3.34 × 105 J/kg. What is the specific heat capacity of the metal of the container?
1700 J/kg K
A child is trying to stack two uniform bricks, each 24 cm long, so they will protrude as far as possible over the edge of a table without tipping over, as shown in the figure. What is the maximum possible overhang distance d?
18 cm
The sum of two vectors of fixed magnitudes has its minimum magnitude when the angle between these vectors is
180°
To determine the height of a flagpole, Abby throws a ball straight up and times it. She sees that the ball goes by the top of the pole after 0.50 s and then reaches the top of the pole again after a total elapsed time of 4.1 s. How high is the pole above the point where the ball was launched? Neglect air resistance.
18m
Find the net work done by friction on a box that moves in a complete circle of radius on a uniform horizontal floor. The coefficient of kinetic friction between the floor and the box is 0.25, and the box weighs
190 J
A string is wrapped tightly around a fixed frictionless pulley that has a moment of inertia of 0.0352 kg m2 and a radius of 12.5 cm. The string is pulled away from the pulley with a constant force of 5.00 N, causing the pulley to rotate. What is the speed of the string after it has unwound 1.25 m if the string does not slip on the pulley?
2.36
The figure shows an object's acceleration-versus-force graph. What is the mass of this object?
2.5 g
The figure shows an object's acceleration-versus-force graph. What is the mass of this object?
2.5 kg
A 3.0-kg mass and a 5.0-kg mass hang vertically at the opposite ends of a very light rope that goes over an ideal pulley. If the masses are gently released, what is the resulting acceleration of the masses?
2.5 m/s2
A rectangular box of negligible mass measures 5.0 m long, 1.0 m wide, and 0.50 m high. How many kilograms of mass can be loaded onto the box before it sinks in a lake having water of density 1000 kg/m3?
2.5 × 103 kg
A person on a diet loses in a week. How many are lost?
2.6 × 103 g/s
How many joules of energy are used by a 1.0-hp motor that runs for 1.0 hour? (1 hp = 746 W)
2.7 MJ
A block is on a frictionless table, on earth. The block accelerates at 5.3 m/s2 when a horizontal force is applied to it. The block and table are set up on the Moon where the acceleration due to gravity is 1.62 m/s2. A horizontal force of 5 N is now applied to the block when it is on the Moon. The acceleration imparted to the block by this force is closest to
2.7 m/s2
A uniform rod weighs 40 N and is 1.0 m long. It is hinged to a wall at the left end, and held in a horizontal position at the right end by a vertical string of negligible weight, as shown in the figure. What is the magnitude of the torque due to the string about a horizontal axis that passes through the hinge and is perpendicular to the rod? The hinge is very small with negligible friction.
20 N m
An object with a mass of 10 kg is initially at rest at the top of a frictionless inclined plane that rises at 30° above the horizontal. At the top, the object is initially 8.0 m from the bottom of the incline, as shown in the figure. When the object is released from this position, it eventually stops at a distance d from the bottom of the inclined plane along a horizontal surface, as shown. The coefficient of kinetic friction between the horizontal surface and the object is 0.20, and air resistance is negligible. Find the distance d.
20 m
An object is dropped from a bridge. A second object is thrown downwards 1.0 s later. They both reach the water 20 m below at the same instant. What was the initial speed of the second object? Neglect air resistance.
20 m/s
The height of the ceiling in a typical home, apartment, or dorm room is closest to
200 cm
What is the value of (8.104)2, written with the correct number of significant figures?
206.3
What is the product of 11.24 and 1.95 written with the correct number of significant figures?
21.9
The figure shows a famous roller coaster ride. You can ignore friction. If the roller coaster leaves point Q from rest, what is its speed at the top of the 25-m peak (point S)?
22m/s
Pulling out of a dive, the pilot of an airplane guides his plane into a vertical circle. At the bottom of the dive, the speed of the airplane is 320 m/s. What is the smallest radius allowable for the vertical circle if the pilot's apparent weight is not to exceed 7.0 times his true weight?
230 m
A 50-kg box is being pushed along a horizontal surface. The coefficient of static friction between the box and the ground is 0.65, and the coefficient of kinetic friction is 0.35. What horizontal force must be exerted on the box for it to accelerate at 1.2 m/s2?
230N
Convert a speed of 4.50 km/h to units of ft/min. (1.00 m = 3.28 ft)
246 ft/min
A 5000-N force compresses a steel block by 0.0025 cm. How much force, applied over the same area, would be needed to compress the block by 0.0125 cm?
25,000 N
An object starts from rest and undergoes uniform acceleration. During the first second it travels 5.0 m. How far will it travel during the third second?
25m
You throw a rock horizontally off a cliff with a speed of 20 m/s and no significant air resistance. After 2.0 s, the magnitude of the velocity of the rock is closest to
28 m/s
A 3.00-m-long ladder, weighing 200 N, leans against a smooth vertical wall with its base on a horizontal rough floor, a distance of 1.00 m away from the wall. The ladder is not completely uniform, so its center of gravity is 1.20 m from its base. What force of friction must the floor exert on the base of the ladder to prevent the ladder from sliding down?
28.3 N
A person running in place on an exercise machine for 10 min uses up 17 kcal (food calories). Another person exercises by repeatedly lifting two 2.5-kg weights a distance of 50 cm. How many repetitions of this exercise are equivalent to 10 minutes of running in place? Assume that the person uses negligible energy in letting down the weights after each lift. (1 cal = 4.186 J)
2900
The temperature in your classroom is closest to
295 K
Two horizontal pipes have the same diameter, but pipe B is twice as long as pipe A. Water undergoes viscous flow in both pipes, subject to the same pressure difference across the lengths of the pipes. If the flow rate in pipe B is what is the flow rate in pipe A?
2Q
Approximately how many pennies (~1.2 mm thick) would you have to stack to reach an average 8-foot ceiling?
2x103
In the number 0.00723, the number of significant figures is.
3
Estimate the number of times the earth will rotate on its axis during a human's lifetime, given that the average age is 75-85 years.
3 × 104
An ideal incompressible fluid flows at 12 m/s in a horizontal pipe. If the pipe widens to twice its original radius, what is the flow speed in the wider section?
3.0 m/s
A 100-kg person sits on a 5-kg bicycle. The total weight is borne equally by the two wheels of the bicycle. The tires are 2.0 cm wide and are inflated to a gauge pressure of 8.0 × 105 Pa. What length of each tire is in contact with the ground?
3.2 cm
A solid uniform sphere is rolling without slipping along a horizontal surface with a speed of 5.5 m/s when it starts up a ramp that makes an angle of 25° with the horizontal. What is the speed of the sphere after it has rolled 3.0 m up as measured along the surface of the ramp?
3.5
The figure shows a graph of the temperature of a pure substance as a function of time as heat is added to it at a constant rate in a closed container. If LF is the latent heat of fusion of this substance and LV is its latent heat of vaporization, what is the value of the ratio LV/LF?
3.5
A child is riding a merry-go-round that is turning at 7.18 rpm. If the child is standing 4.65 m from the center of the merry-go-round, how fast is the child moving?
3.50 m/s
A solid uniform disk of diameter 3.20 m and mass 42 kg rolls without slipping to the bottom of a hill, starting from rest. If the angular speed of the disk is 4.27 rad/s at the bottom, how high did it start on the hill?
3.57
A 12-L volume of oil is subjected to pressure which produces a volume strain of -3.0 × 10-4. The bulk modulus of the oil is 6.0 × 109 Pa and is independent of the pressure. The reduction in the volume of the oil in milliliters is closest to
3.6 mL
The base of a metal block, which is fixed in place, measures 90 cm by 90 cm, and the height of the block is 60 cm. A force, applied to the upper face and parallel to it, produces a shear strain of 0.0060. The shear modulus of this metal is 3.0 × 1010 Pa. The displacement of the upper face, in the direction of the applied force is closest to
3.6mm
In addition to 1 m = 39.37 in., the following exact conversion equivalents are given: and 1 min = 60 s. If a particle has a velocity of 8.4 miles per hour,its velocity, in m/s, is closest to
3.8 m/s
A solid wooden door, 90 cm wide by 2.0 m tall, has a mass of 35 kg. It is open and at rest. A small 500-g ball is thrown perpendicular to the door with a speed of 20 m/s and hits the door 60 cm from the hinged side, causing it to begin turning. The ball rebounds along the same line with a speed of 16.0 m/s relative to the ground. How much energy is lost during this collision?
30 J
A very small 51-g steel ball is released from rest and falls vertically onto a steel plate. The ball strikes the plate and is in contact with it for 0.50 ms. The ball rebounds elastically and returns to its original height. The total time interval for a round trip is 3.00 s. What is the magnitude of the average force exerted on the ball by the plate during contact with the plate?
3000 N
Under standard conditions, the density of air is 1.29 kg/m3. What is the mass of the air inside a room measuring 4.0 m × 3.0 m × 2.0 m?
31 kg
How many moles are there in 2.00 kg of copper? The atomic weight of copper is 63.5 g/mol and its density is 8.90 g/cm3.
31.5
In grinding a steel knife, the metal can get as hot as 400°C. If the blade has a mass of 80 g, what is the minimum amount of water needed at 20°C if the water is to remain liquid and not rise above 100°C when the hot blade is quenched in it? The specific heat of the steel is 0.11 cal/g C° and the specific heat of water is 1.0 cal/g C°.
33 g
What is the minimum energy needed to lift a 1.0-kg rocket to a height of 200 km and to give it a speed of 8.0 km/s at that height? (Neglect air resistance and the small decrease in g over that distance.)
34 MJ
An athlete participates in an interplanetary discus throw competition during an Olympiad that takes place on a planet where the acceleration due to gravity is 9.7 m/s2. He throws the discus with an initial velocity of 20 m/s at an angle of 60° from the vertical. Neglecting air resistance and the height of the discus at the point of release, what is the range of the discus?
36 m
A man in a gym is holding an 8.0-kg weight at arm's length, a distance of 0.55 m from his shoulder joint. What is the torque about his shoulder joint due to the weight if his arm is held at 30° below the horizontal?
37 N m
An oxygen molecule, O2, falls in a vacuum. From what height must it fall so that its translational kinetic energy at the bottom of its fall equals the average translational kinetic energy of an oxygen molecule at 920 K? The mass of one O2 molecule is 5.312 × 10-26 kg, and the Boltzmann constant is 1.38 × 10-23 J/K. Neglect air resistance and assume that g remains constant at 9.8 m/s2 throughout the fall of the molecule.
37 km
Planet Z-34 has a mass equal to one-third that of Earth and a radius equal to one-third that of Earth. With g representing, as usual, the acceleration due to gravity at the surface of Earth, the acceleration due to gravity at the surface of Z-34 is
3g
Two uniform solid spheres have the same mass, but one has twice the radius of the other. The ratio of the larger sphere's moment of inertia about a central axis to that of the smaller sphere is
4
A polar bear of mass 200 kg stands on an ice floe that is a uniform 1.0 m thick. What is the minimum area of the floe that will just support the bear in saltwater of density 1030 kg/m3? The density of ice is 980 kg/m3.
4 m2
The coefficient of volume expansion of a certain olive oil is 0.68 × 10-3 K-1. A 1.0-L glass beaker is filled to the brim with olive oil at room temperature. The beaker is placed on a range and the temperature of the oil and beaker increases by 25 °C. As a result, 0.0167 L of olive oil spills over the top of the beaker. Which of the following values is closest to the coefficient of linear expansion of the glass from which the beaker is made?
4 × 10-6 K-1
A uniform solid cylinder of mass 10 kg can rotate about a frictionless axle through its center O, as shown in the cross-sectional view in the figure. A rope wrapped around the outer radius R1 = 1.0 m exerts a force of magnitude F1 = 5.0 N to the right. A second rope wrapped around another section of radius R2 = 0.50 m exerts a force of magnitude F2 = 6.0 N downward. What is the angular acceleration of the cylinder?
4.0
On an alien planet, an object moving at 4.0 m/s on the horizontal ground comes to rest after traveling a distance of 10 m. If the coefficient of kinetic friction between the object and the surface is 0.20, what is the value of g on that planet?
4.0 m/s2
A cylinder, semicircular in cross-section, is 10 m long and 5.0 m in radius. It is completely submerged, with its flat bottom side horizontal and 8.0 m below the water surface, as shown in the figure. What is the magnitude of the net force on the curved upper surface of the half-cylinder? Neglect atmospheric pressure.
4.0 x 10 6 N
What is the result of 1.58 ÷ 3.793 written with the correct number of significant figures?
4.17x10-1
A sand mover at a quarry lifts 2,000 kg of sand per minute a vertical distance of 12 m. The sand is initially at rest and is discharged at the top of the sand mover with speed 5.0 m/s into a loading chute. What minimum power must be supplied to this machine?
4.3 kW
One of the dangers of tornados and hurricanes is the rapid drop in air pressure that is associated with such storms. Assume that the air pressure inside of a sealed house is 1.02 atm when a hurricane hits. The hurricane rapidly decreases the external air pressure to 0.910 atm. What net outward force is exerted on a square window of the house that is on each side? (1.00 atm = 1.01 × 105 Pa)
4.59 x 10 4 N
When Jeff ran up a hill at 7.0 m/s, the horizontal component of his velocity vector was 5.1 m/s. What was the vertical component of Jeff's velocity?
4.8 m/s
A 0.140 kg baseball is thrown horizontally with a velocity of 28.9 m/s. It is struck with a constant horizontal force that lasts for 1.85 ms, which results in a velocity of 37.0 m/s in the opposite direction. What was the magnitude of the horizontal force?
4.99
In an electric furnace used for refining steel, the temperature is monitored by measuring the radiant power emitted through a small hole in the wall of the furnace, of area 0.5 cm2. This hole acts like a perfect blackbody radiator having the same temperature as the interior of the furnace. If the temperature of the furnace (and therefore of the hole) is to be maintained at 1650°C, how much power will the hole radiate?
40 W
Which of the following quantities has units of a displacement? (There could be more than one correct choice.)
40 km southwest 186,000 mi
A golf club exerts an average horizontal force of 1000 N on a 0.045-kg golf ball that is initially at rest on the tee. The club is in contact with the ball for 1.8 ms. What is the speed of the golf ball just as it leaves the tee?
40 m/s
A 0.24 kg blob of clay is thrown at a wall with an initial horizontal velocity of If the clay comes to a stop in what is the average horizontal force on the clay due to the wall?
42 N
As shown in the figure, a bullet of mass 0.010 kg moving horizontally suddenly strikes a block of wood of mass 1.5 kg that is suspended as a pendulum. The bullet lodges in the wood, and together they swing upward a vertical distance of 0.40 m. The length of the string is 2.0 m. What was the speed of the bullet just before it struck the wooden block?
420 m/s
If you add 700 kJ of heat to 700 g of water originally at 70.0°C, how much water is left in the container? The latent heat of vaporization of water is 22.6 × 105 J/kg, and its specific heat capacity is 4186 J/kg K.
429
If you add 700 kJ of heat to 700 g of water originally at 70.0°C, how much water is left in the container? The latent heat of vaporization of water is 22.6 × 105 J/kg, and its specific heat capacity is 4186 J/kg K
429 g
A jet plane is launched from a catapult on an aircraft carrier. In 2.0 s it reaches a speed of 42 m/s at the end of the catapult. Assuming the acceleration is constant, how far did it travel during those 2.0 s?
42m
A person throws a ball horizontally from the top of a building that is 24.0 m above the ground level. The ball lands 100 m down range from the base of the building. What was the initial velocity of the ball? Neglect air resistance and use g = 9.81 m/s2.
45.2 m/s
A 90-g aluminum calorimeter contains 390 g of water at an equilibrium temperature of A piece of metal, initially at is added to the calorimeter. The final temperature at equilibrium is 32° C. Assume there is no external heat exchange. The specific heat capacities of aluminum and water are 910 J/kg K (aluminum) and 4190 J/kg K (water). What is the specific heat capacity of the 160-g piece of metal?
470
A test rocket at ground level is fired straight up from rest with a net upward acceleration of 20 m/s2. After 4.0 s, the motor turns off but the rocket continues to coast upward with insignificant air resistance. What maximum elevation does the rocket reach?
490m
If a person's pulse rate is 70-80 bpm, approximately how many times does an average human heart beat in a year?
4x107
A runner runs around a track consisting of two parallel lines 96 m long connected at the ends by two semicircles with a radius of 49 m. She completes one lap in 100 seconds. What is her average speed?
5 m/s
A person is using a rope to lower a 5.0-N bucket into a well with a constant speed of 2.0 m/s. What is the magnitude of the force exerted by the rope on the bucket?
5.0 N
A round coin has a diameter of 19.55 mm, a thickness of 1.55 mm, and a mass of 2.50 g. What is its density?
5.37 × 103 kg/m3
The coefficient of linear expansion for aluminum is 1.8 × 10-6 K-1. What is its coefficient of volume expansion?
5.4 × 10-6 K-1
A 385-g tile hangs from one end of a string that goes over a pulley with a moment of inertia of and a radius of 15.0 cm. A mass of 710 g hangs from the other end of the string. When the tiles are released, the larger one accelerates downward while the lighter one accelerates upward. The pulley has no friction in its axle and turns without the string slipping. What is the tension in the string on the side of the 710-g tile?
5.59 N
If 4.0 J of work are performed in stretching an ideal spring with a spring constant (force constant) of 2500 N/m, by what distance is the spring stretched?
5.7 cm
Asteroid Ida was photographed by the Galileo spacecraft in 1993, and the photograph revealed that the asteroid has a small moon, which has been named Dactyl. From the dimensions of Ida and its general features, one can estimate the mass of Ida to be 4.5 × 1016 kg, and the distance between Dactyl and Ida is approximately 90 km. Assuming a circular orbit, what would be the orbital speed of Dactyl? (G = 6.67 × 10-11 N m2/kg2)
5.8 m/s
A light-year is the distance that light travels in one year. The speed of light is 3.00 × 108 m/s. How many miles are there in one light-year? (1 mi = 1609 m, 1 y = 365 d)
5.88 × 1012 mi
A solid cylindrical bar conducts heat at a rate of 25 W from a hot to a cold reservoir under steady state conditions. If both the length and the diameter of this bar are doubled, the rate at which it will conduct heat between these reservoirs will be
50 W
Which requires more work, increasing a car's speed from 0 mph to 30 mph or from 50 mph to 60 mph?
50 mph to 60 mph
A piano mover raises a 1000-N piano at a constant speed using a very light rope in a frictionless pulley system, as shown in the figure. With what force is the mover pulling down on the rope?
500 N
A 1000-kg car is moving at 15 km/h. If a 2000-kg truck has 23 times the kinetic energy of the car, how fast is the truck moving?
51 km/h
A machinist turns on the power on to a grinding wheel at time t = 0 s. The wheel accelerates uniformly from rest for 10 s and reaches the operating angular speed of The wheel is run at that angular velocity for 30 s, and then power is shut off. The wheel slows down uniformly at until the wheel stops. What is the total number of revolutions made by the wheel in this situation?
510
What is the proper banking angle for an Olympic bobsled to negotiate a 100-m radius turn at 35 m/s without skidding?
51°
At what temperature is the rms speed of hydrogen molecules, H2, which have a molecular weight of 2.02 g/mole, equal to 2.0 km/s? The Boltzmann constant is 1.38 × 10-23 J/K and NA = 6.022 × 1023 molecules/mol.
51°C
Two metal rods, one silver and the other gold, are attached to each other end-to-end. The free end of the silver rod is immersed in a steam chamber at 100°C, and the free end of the gold rod in an ice water bath at 0°C. The rods are both 5.0 cm long and have a square cross-section that is 2.0 cm on a side. No heat is exchanged between the rods and their surroundings, except at the ends. What is the temperature at the point where the two rods are in contact with one another? The thermal conductivity of silver is 417 W/m K, and that of gold is 291 W/m K.
59 C
A spring-loaded dart gun is used to shoot a dart straight up into the air, and the dart reaches a maximum height of 24 meters. The same dart is shot up a second time from the same gun, but this time the spring is compressed only half as far (compared to the first shot). How far up does the dart go this time (neglect all friction and assume the spring is ideal)?
6.0 m
A satellite that is in a circular orbit 230 km above the surface of the planet Zeeman-474 has an orbital period of 89 min. The radius of Zeeman-474 is 6.38 × 106 m. What is the mass of this planet? (G = 6.67 × 10-11 N m2/kg2)
6.0 × 1024 kg
A figure skater rotating at 5.00 rad/s with arms extended has a moment of inertia of 2.25 kg m2. If he pulls in his arms so his moment of inertia decreases to 1.80 kg m2, what will be his new angular speed?
6.25 rad/sec
A golf ball of mass 0.050 kg is at rest on the tee. Just after being struck, it has a velocity of 102 m/s. If the club and ball were in contact for what is the average force exerted on the ball by the club?
6.3 kN
The coefficient of linear expansion of copper is 17 × 10-6 K-1. A block of copper 30 cm wide, 45 cm long, and 10 cm thick is heated from 0°C to 100°C What is the change in the volume of the block?
6.9 × 10-5 m3
A torque of 12 N m is applied to a solid, uniform disk of radius 0.50 m. If the disk accelerates at what is the mass of the disk?
60 kg
A steel pipe 36.0 m long, installed when the temperature was is used to transport superheated steam at a temperature of Steel's coefficient of linear expansion is . The pipe is allowed to expand freely when the steam is transported. What is the increase in the length of the pipe when it is used with the superheated steam?
60 mm
A truck is using a hook to tow a car whose mass is one quarter that of the truck. If the force exerted by the truck on the car is 6000 N, then the force exerted by the car on the truck is
6000 N
A 1000-kg whale swims horizontally to the right at a speed of 6.0 m/s. It suddenly collides directly with a stationary seal of mass 200 kg. The seal grabs onto the whale and holds fast. What is the momentum of these two sea creatures just after their collision? You can neglect any drag effects of the water during the collision.
6000 kg m/s
A 1200-kg car is pulling a 500-kg trailer along level ground. Friction of the road on the trailer is negligible. The car accelerates with an acceleration of 1.3 m/s2. What is the force exerted by the car on the trailer?
650 N
A student adds two displacement vectors that have the magnitudes of 12.0 m and 5.0 m. What is the range of possible answers for the magnitude of the resultant vector?
7.0m and 17.0m
Vector has a magnitude of 6.0 m and points 30° south of east. Vector has a magnitude of 4.0 m and points 30° west of south. The resultant vector + is given by
7.2 m at an angle of 64° south of east.
An ice skater has a moment of inertia of 5.0 kg m2 when her arms are outstretched, and at this time she is spinning at 3.0 rev/s. If she pulls in her arms and decreases her moment of inertia to 2.0 kg m2, how fast will she be spinning?
7.5 rev/sec
A solid object floats in water with three-fourths of its volume beneath the surface. What is the object's density? The density of water is 1000 kg/m3.
750
If the work done to stretch an ideal spring by 4.0 cm is 6.0 J, what is the spring constant (force constant) of this spring?
7500 N/m
At a given point above Earth's surface, the acceleration due to gravity is equal to What is the altitude of this point above Earth's surface?(G = 6.67 × 10-11 N m2/kg2, Mearth = 5.97 × 1024 kg, Rearth = 6.38 × 106 m)
770 km
A styrofoam sphere of radius R has a density . You now carefully compress the sphere so its radius is R/2. What is the density of the compressed sphere?
8
A child is riding a merry-go-round that has an instantaneous angular speed of 1.25 rad/s and an angular acceleration of 0.745 rad/s2. The child is standing 4.65 m from the center of the merry-go-round. What is the magnitude of the linear acceleration of the child?
8.05 m/s2
Two metal rods, one silver and the other gold, are attached to each other end-to-end. The free end of the silver rod is immersed in a steam chamber at 100°C, and the free end of the gold rod in an ice water bath at 0°C. The rods are both 5.0 cm long and have a square cross-section that is 2.0 cm on a side. No heat is exchanged between the rods and their surroundings, except at the ends. How much total heat flows through the two rods each minute? The thermal conductivity of silver is 417 W/m K, and that of gold is 291 W/m K.
8.2 kJ
An object has a volume of 4.0 m3 and weighs 40,000 N. What will its apparent weight be in water of density 1000 kg/m3?
800N
What is the angular speed, in rad/s, of a flywheel turning at 813.0 rpm?
85.14
A 1500-kg car accelerates from rest to 25 m/s in 7.0 s. What is the average power delivered by the engine? (1 hp = 746 W)
90 hp
An ideal spring with a spring constant (force constant) of is stretched from equilibrium to 2.9 m. How much work is done in the process?
93 J
How much work would a child do while pulling a 12-kg wagon a distance of with a force?
95 J
In a section of horizontal pipe with a diameter of 3.0 cm, the pressure is 100 kPa and water is flowing with a speed of 1.5 m/s. The pipe narrows to 2.0 cm. What is the pressure in the narrower region? Treat the water as an ideal incompressible fluid.
95 kPa
A bullet shot straight up returns to its starting point in 10 s. What is the initial speed of the bullet, assuming negligible air resistance?
98 m/s
A cubical block of stone is lowered at a steady rate into the ocean by a crane, always keeping the top and bottom faces horizontal. Which one of the following graphs best describes the gauge pressure p on the bottom of this block as a function of time t if the block just enters the water at time t = 0 s?
A
The figure shows a graph of the position of a moving object as a function of time. (a) What is the average velocity of the object from t = 0 s to t = 4.0 s? (b) What is the average velocity of the object from t = 0 s to t = 6.0 s?
A = 10 m/s B = 0 m/s
A race car circles 10 times around a circular 8.0-km track in 20 min. Using SI units (a) what is its average speed for the ten laps? (b) what is its average velocity for the ten laps?
A = 6.67 m/s B = 6.67 m/s
Which of the following situations is impossible?
An object has constant non-zero velocity and changing acceleration.
A 1-kg ball is released from a height of 6 m, and a 2-kg ball is released from a height of 3 m. Air resistance is negligible as they fall. Which of the following statements about these balls are correct? (There could be more than one correct choice.)
As they reach the ground, the 1-kg ball will be moving faster than the 2-kg ball. Both balls will reach the ground with the same kinetic energy.
An auto manufacturer advertises that their car can go "from zero to sixty in eight seconds." This is a description of what characteristic of the car's motion?
Average acceleration
A child standing on a bridge throws a rock straight down. The rock leaves the child's hand at time t = 0 s. If we take upward as the positive direction, which of the graphs shown below best represents the acceleration of the stone as a function of time?
B
A cubical block of stone is lowered at a steady rate into the ocean by a crane, always keeping the top and bottom faces horizontal. Which one of the following graphs best describes the buoyant force B on this block as a function of time t if the block just enters the water at time t = 0 s?
B
Shown below are the velocity and acceleration vectors for an object in several different types of motion. In which case is the object slowing down and turning to its right?
B
Consider a uniform hoop of radius R and mass M rolling without slipping. Which is larger, its translational kinetic energy or its rotational kinetic energy?
Both are equal
The figure shows a graph of the position x of two cars, C and D, as a function of time t According to this graph, which statements about these cars must be true?
Both cars have the same acceleration. The cars meet at time t = 10 s.
A mole of diatomic oxygen molecules and a mole of diatomic nitrogen molecules are at STP. Which statements are true about these molecules? (There could be more than one correct choice.)
Both gases have the same number of molecules. Both gases have the same average kinetic energy per molecule
A 4.0 kg object is moving with speed 2.0 m/s. A 1.0 kg object is moving with speed 4.0 m/s. Both objects encounter the same constant braking force, and are brought to rest. Which object travels the greater distance before stopping?
Both objects travel the same distance.
You and your friend, who weighs the same as you, want to go to the top of the Eiffel Tower. Your friend takes the elevator straight up. You decide to walk up the spiral stairway, taking longer to do so. Compare the gravitational potential energy of you and your friend, after you both reach the top.
Both of you have the same amount of gravitational potential energy at the top.
Mary and Debra stand on a snow-covered roof. They both throw snowballs with the same initial speed, but in different directions. Mary throws her snowball downward, at 30° below the horizontal; Debra throws her snowball upward, at 30° above the horizontal. Which of the following statements are true about just as the snowballs reach the ground below? (There could be more than one correct choice.)
Both snowballs will hit the ground with the same speed. Mary's snowball reaches the ground before Debra's snowball.
A block of mass m sits at rest on a rough inclined ramp that makes an angle with the horizontal. What must be true about normal force F on the block due to the ramp?
F = mg cosΘ
A boat loaded with rocks is floating in a swimming pool. If the rocks are thrown into the pool, the water level in the pool, after the rocks have settled to the bottom,
Falls
If the sum of the external torques on an object is zero, then the sum of the external forces on it must also be zero.
False
If you swing a bucket of water fast enough in a vertical circle, at the highest point the water does not spill out. This happens because an outward force balances the pull of gravity on the water.
False
In order to get an object moving, you must push harder on it than it pushes back on you.
False
Scientists use the metric system chiefly because it is more accurate than the English system.
False
The magnitude of the resultant of two vectors cannot be less than the magnitude of either of those two vectors.
False @C
A stone is held at a height h above the ground. A second stone with four times the mass of the first one is held at the same height. The gravitational potential energy of the second stone compared to that of the first stone is
Four times as much
A spinning ice skater on extremely smooth ice is able to control the rate at which she rotates by pulling in her arms. Which of the following statements are true about the skater during this process? (There could be more than one correct choice.)
Her angular momentum = constant
If the absolute temperature of an object is tripled, the thermal power radiated by this object (assuming that its emissivity and size are not affected by the temperature change) will
Inc by a factor of 81
A piece of wood is floating in a bathtub. A second piece of wood sits on top of the first piece, and does not touch the water. If the top piece is taken off and placed in the water, what happens to the water level in the tub?
It does not change
A piece of iron rests on top of a piece of wood floating in a bathtub. If the iron is removed from the wood, and kept out of the water, what happens to the water level in the tub?
It goes down
Two blocks are made of the same material, but one has twice the volume of the other block. Which block will have the greater shear modulus?
It will be the same for both of them.
Two wires are made out of the same metal, but one wire is twice as long as the other wire. Which wire will have the greatest elastic modulus?
It will be the same for both wires.
A projectile is fired from ground level on a horizontal plain. If the initial speed of the projectile is now doubled, and we neglect air resistance,
It will quadruple
Suppose that a car traveling to the east (+x direction) begins to slow down as it approaches a traffic light. Which statement concerning its acceleration must be correct?
Its acceleration is in the -x direction.
Which one of the following quantities is the smallest unit of heat energy?
Joule
A heavy stone and a light stone are released from rest in such away that they both have the same amount of gravitational potential energy just as they are released. Air resistance is negligibly small. Which of the following statements about these stones are correct? (There could be more than one correct choice.)
Just as it reaches the ground, the light stone is traveling faster than the heavy stone. The stones both have the same kinetic energy just as they reach the ground. The initial height of the light stone is greater than the initial height of the heavy stone.
Two men, Joel and Jerry, push against a car that has stalled, trying unsuccessfully to get it moving. Jerry stops after 10 min, while Joel is able to push for 5.0 min longer. Compare the work they do on the car.
Neither of them does any work.
A thermally isolated system is made up of a hot piece of aluminum and a cold piece of copper, with the aluminum and the copper in thermal contact. The specific heat capacity of aluminum is more than double that of copper. Which object experiences the greater magnitude gain or loss of heat during the time the system takes to reach thermal equilibrium?
Neither one; both of them experience the same size gain or loss of heat.
A very light ping-pong ball moving east at a speed of 4 m/s collides with a very heavy stationary bowling ball. The Ping-Pong ball bounces back to the west, and the bowling ball moves very slowly to the east. Which object experiences the greater magnitude impulse during the collision?
Neither; both experienced the same magnitude impulse.
A crate is sliding down an inclined ramp at a constant speed of 0.55 m/s. The vector sum of all the forces acting on this crate must point
None of these choices is correct.
In the figure, determine the character of the collision. The masses of the blocks, and the velocities before and after, are shown. The collision is
Perfectly elastic
Water flows through a pipe. The diameter of the pipe at point B is larger than at point A. Where is the water pressure greatest?
Point B
If the units of your answer are kg m2/s3, which of the following types of quantities could your answer be?(There could be more than one correct choice.)
Power
Ball A is dropped from the top of a building. One second later, ball B is dropped from the same building. Neglect air resistance. As time progresses, the difference in their speeds
Remains constant
As shown in the figure, fluid fills a container having several sections. At which of the indicated points is the pressure greatest?
Same at each point
Consider two less-than-desirable options. In the first you are driving 30 mph and crash head-on into an identical car also going 30 mph. In the second option you are driving 30 mph and crash head-on into a stationary brick wall. In neither case does your car bounce back from the thing it hits, and the collision time is the same in both cases. Which of these two situations would result in the greater impact force on your car?
Same force in both cases
A firecracker explodes in midair and breaks up into many fragments. Which of the following statements are true regarding conditions immediately before and immediately after the explosion:I. The total momentum of the fragments is equal to the original momentum of the firecracker. II. The total kinetic energy of the fragments is equal to the original kinetic energy of the firecracker.
Statement I only
Two friends are standing on opposite ends of a canoe that is initially at rest with respect to a frictionless lake. The person in the front throws a very massive ball toward the back, and the person in the back catches it. After the ball is caught, the canoe is
Stationary
Two boxes are connected to each other by a string as shown in the figure. The 10-N box slides without friction on the horizontal table surface. The pulley is ideal and the string has negligible mass. What is true about the tension T in the string?
T < 30 N
Inside of a train a ball of weight W is hanging by a light wire at rest from the ceiling. The wire makes an angle with the ceiling, as shown in the figure. Which one of the following conditions must be true about the tension T in the wire?
T sin = W
If atmospheric pressure increases by an amount p, which of the following statements about the pressure in a lake is true? (There could be more than one correct choice.)
The absolute (total) pressure increases by p. The gauge pressure does not change.
A 10-kg piece of aluminum sits at the bottom of a lake, right next to a 10-kg piece of lead, which is much denser than aluminum. Which one has the greater buoyant force on it?
The aluminum
Salt water has greater density than fresh water. A boat floats in both fresh water and in salt water. Where is the buoyant force greater on the boat?
The buoyant force is the same in both cases.
A fireman is sliding down a fire pole. As he speeds up, he tightens his grip on the pole, thus increasing the vertical frictional force that the pole exerts on the fireman. When the force on his hands equals his weight, what happens to the fireman?
The fireman continues to descend, but with constant speed.
A heavy sled and a light sled, both moving horizontally with the same speed, suddenly slide onto a rough patch of snow and eventually come to a stop. The coefficient of kinetic friction between the sleds and the rough snow is the same for both of them. Which of the following statements about these sleds are correct? (There could be more than one correct choice.)
The friction from the snow will do more negative work on the heavy sled than on the light sled. Both sleds will slide the same distance on the rough snow before stopping.
A heavy dart and a light dart are launched vertically by identical ideal springs. Both springs were initially compressed by the same amount. There is no significant air resistance. Which of the following statements about these darts are correct? (There could be more than one correct choice.)
The light dart goes higher than the heavy dart. At the maximum height, both darts have the same gravitational potential energy.
Two objects of different masses have momentum of equal, non-zero magnitude. Which object has more kinetic energy?
The lighter object
A closed cubical chamber resting on the floor contains oil and a piston. If you push down on the piston hard enough to increase the pressure just below the piston by an amount p, which of the following statements is correct? (There could be more than one correct choice.)
The pressure everywhere in the oil will increase by p. The increase in the force on the top of the chamber will be the same as the increase in the force on the bottom of the chamber.
Which one of the following is an accurate statement?
The ratio of tensile stress to tensile strain is called Young's modulus.
If you stood on a planet having a mass four times that of Earth's mass, and a radius two times that of Earth's radius, you would weigh
The same as on earth
A small car meshes with a large truck in a head-on collision. Which of the following statements concerning the magnitude of the average force during the collision is correct?
The small car and the truck experience the same average force.
In which case will the speed of the stone be greatest when it hits the water below if there is no significant air resistance?
The speed is all the same
A stone can slide down one of four different frictionless ramps, as shown in the figure. For which ramp will the speed of the ball be the greatest at the bottom?
The speed of the ball will be the same for all ramps.
A girl throws a stone from a bridge. Consider the following ways she might throw the stone.
The speed will be the same in all cases.
On a cold day, a piece of metal feels much colder to the touch than a piece of wood. This is due to the difference in which one of the following physical properties of these materials?
Thermal conductivity
Two objects are thrown from the top of a tall building. One is thrown up, and the other is thrown down, both with the same initial speed. What are their speeds when they hit the street? Neglect air resistance.
They are traveling at the same speed.
In a collision between two unequal masses, which mass receives a greater magnitude impulse?
They receive equal impulses
A 25-kg piece of equipment can be hung by steel wires of length 1.00 m, 2.00 m, or 3.00 m. If all the wires have the same diameter, which one will stretch the greatest percent?
They will all stretch by the same percent.
Consider a car that travels between points A and B. The car's average speed can be greater than the magnitude of its average velocity, but the magnitude of its average velocity can never be greater than its average speed.
True
The magnitude of a vector an only zero if all of its components are zero.
True
The root-mean-square speed of the molecules of an ideal gas is v. The gas is now slowly compressed to one-half its original volume with no change in temperature. What is the root-mean-square speed of the molecules now?
V
The slope of a position versus time graph gives
Velocity
The graph in the figure shows the tensile stress as a function of the tensile strain in a certain wire. What does the slope of this graph give us for this wire?
Young's modulus for the material of the wire
An object is moving with constant non-zero velocity in the +x direction. The position versus time graph of this object is
a straight line making an angle with the time axis.
Consider a flat steel plate with a hole through its center as shown in the figure. When the temperature of the plate is increased, the hole will
always expand with the plate.
If the answer to your calculation has units of kg m2/s, what type of quantity could it be? (There could be more than one correct choice).
angular momentum
Tensile stress is
applied force per cross-sectional area.
If, with steady state heat flow established, you double the thickness of a wall built from solid uniform material, the rate of heat loss for a given temperature difference across the thickness will
become one-half its original value.
In the figure, determine the character of the collision. The masses of the blocks, and the velocities before and after, are shown. The collision is
completely inelastic.
The process in which heat flows by the mass movement of molecules from one place to another is known as
convection
As you are leaving a building, the door opens outward. If the hinges on the door are on your right, what is the direction of the angular velocity of the door as you open it?
down
A boat loaded with rocks is floating in a swimming pool. If the rocks are thrown into the pool, the water level in the pool, after the rocks have settled to the bottom,
falls
If the sum of both the external torques and the external forces on an object is zero, then the object must be at rest.
false
If the velocity of an object is zero at some point, then its acceleration must also be zero at that point.
false
A steel ball sinks in water but floats in a pool of mercury, which is much denser than water. Where is the buoyant force on the ball greater?
floating on the mercury
Jill does twice as much work as Jack does and in half the time. Jill's power output is
four times Jack's power output.
Joe and Bill throw identical balls vertically upward. Joe throws his ball with an initial speed twice as high as Bill. If there is no air resistance, the maximum height of Joe's ball will be
four times that of Bill's ball.
A satellite encircles Mars at a distance above its surface equal to 3 times the radius of Mars. If gm is the acceleration due to gravity at the surface of Mars, what is the acceleration due to gravity at the location of the satellite?
gm/16
If the absolute temperature of an object is tripled, the thermal power radiated by this object (assuming that its emissivity and size are not affected by the temperature change) will
increase by a factor of 81
Halley's Comet is in a highly elliptical orbit around the sun. Therefore the orbital speed of Halley's Comet, while traveling around the sun,
increases as it nears the Sun
Two objects are dropped from a bridge, an interval of 1.0 s apart. Air resistance is negligible. During the time that both objects continue to fall, their separation
increases.
An object moving in the +x direction experiences an acceleration of +2.0 m/s2. This means the object
is increasing its velocity by 2.0 m/s every second.
A piece of iron sinks to the bottom of a lake where the pressure is 21 times what it is at the surface. Which statement best describes what happens to the density of that piece of iron?
its density increases slightly.
Which of the following are SI units of Young's modulus? (There could be more than one correct choice.)
kg/m s2
An egg falls from a bird's nest in a tree and feels no effects due to the air. As it falls,
only its mechanical energy is conserved
On a horizontal frictionless air table, a puck runs into an ideal horizontal spring that is fastened to the table. The puck compresses the spring by 15 cm before coming to rest. During the compression process, which quantities are conserved?
only the mechanical energy (kinetic plus potential) of the puck
If + = and their magnitudes are given by A + B = C, then the vectors and are oriented
parallel to each other (in the same direction).
A car goes around a circular curve on a horizontal road at constant speed. What is the direction of the friction force on the car due to the road?
perpendicular to the curve inward
The rotating systems shown in the figure differ only in that the two identical movable masses are positioned a distance r from the axis of rotation (left), or a distance r/2 from the axis of rotation (right). If you release the hanging blocks simultaneously from rest, and call tL the time taken by the block on the left and tR the time taken by the block on the right to reach the bottom, respectively, then
tL > tR
When you blow some air above a paper strip, the paper rises. This happens because
the air above the paper moves faster and the pressure is lower.
The reason an astronaut in an earth satellite feels weightless is that
the astronaut is falling
The absolute temperature of an ideal gas is directly proportional to which of the following quantities?
the average kinetic energy of its molecules
The current definition of the standard meter of length is based on
the distance traveled by light in a vacuum.
Two objects, one of mass m and the other of mass 2m, are dropped from the top of a building. If there is no air resistance, when they hit the ground
the heavier one will have twice the kinetic energy of the lighter one.
A waiter fills your water glass with ice water (containing many ice cubes) such that the liquid water is perfectly level with the rim of the glass. As the ice melts,
the liquid-water level remains flush with the rim of the glass.
The current definition of the standard kilogram of mass is based on
the mass a particular object kept in France.
When a car goes around a banked circular curve at the proper speed speed for the banking angle, what force cause it to follow the circular path?
the normal force from the road
Tensile strain is
the ratio of the change in length to the original length.
James and John dive from an overhang into the lake below. James simply drops straight down from the edge. John takes a running start and jumps with an initial horizontal velocity of 25 m/s. If there is no air resistance, when they reach the lake below
the splashdown speed of John is larger than that of James.
Two metal spheres are made of the same material and have the same diameter, but one is solid and the other is hollow. If their temperature is increased by the same amount,
the two spheres remain of equal size.
During World War I, Germany used a "Big Bertha" cannon to hurl shells into Paris 30 miles away. This gun also had a very long barrel. What was the reason for using a long barrel in these guns?
to allow the force of the expanding gases from the gunpowder to act for a longer time
If an object remains at rest, then the sum of both the external torques and the external forces on the object must be zero.
true
The magnitude of a vector can never be less than the magnitude of any of its components.
true
The root-mean-square speed of the molecules of an ideal gas is v. The gas is now slowly compressed to one-half its original volume with no change in temperature. What is the root-mean-square speed of the molecules now?
v
A sample of an ideal gas is heated and its Kelvin temperature doubles. If the root-mean-square speed of its molecules was originally v, what is the new root-mean-square speed?
v√2
When is the average velocity of an object equal to the instantaneous velocity?
when the velocity is constant
A marathon is and long. Estimate how many strides (left foot-fall to left foot-fall = 8') would be required to run a marathon.
~17,000
An object hits a wall and bounces back with half of its original speed. What is the ratio of the final kinetic energy to the initial kinetic energy of the object?
¼ Which one has larger kinetic energy: a 500-kg object moving at 40 m/s or a 1000-kg object moving at 20 m/s? @The 500-kg object
You are driving home on a weekend from school at 55 mi/h for 110 miles. It then starts to snow and you slow to 35 mi / h. You arrive home after driving 4 hours and 15 minutes. Approximately, how far is your hometown from school?
190 mi
A stone is thrown with an initial upward velocity of 7.0 m/s and experiences negligible air resistance. If we take upward as the positive direction, what is the velocity of the stone after 0.50 s?
2.1 m/s
A baseball is hit with a bat and, as a result, its direction is completely reversed and its speed is doubled. If the actual contact with the bat lasts 0.45 s, what is the ratio of the magnitude of the average acceleration of the ball to its original speed?
2.2 s-1
A car starts from rest and accelerates uniformly at 3.0 m/s2 toward the north. A second car starts from rest 6.0 s later at the same point and accelerates uniformly at 5.0 m/s2 toward the north. How long after the second car starts does it overtake the first car?
21sec
0.00325 × 10-8 cm can also be expressed in mm as
3.25 × 10-10 mm.
A ball is thrown downward in the absence of air resistance. After it has been released, which statement(s) concerning its acceleration is correct? (There could be more than one correct choice.)
Its acceleration is constant.
A submarine must travel how fast (with respect to the water) and be pointed in what direction such that it moves 10 m/s directly northward (relative to the earth) if the water moves westward at 5.0 m/s?
Northwest 15 m/s
In an air-free chamber, a pebble is thrown horizontally, and at the same instant a second pebble is dropped from the same height. Compare the times of fall of the two pebbles.
They hit at the same time
You are trying to cross a river that flows toward the south with a strong current. You start out in your motorboat on the east bank desiring to reach the west bank directly west from your starting point. You should head your motorboat
in a general northwesterly direction.
From the edge of a roof top you toss a green ball upwards with initial speed v0 and a blue ball downwards with the same initial speed. Air resistance is negligible. When they reach the ground below
the two balls will have the same speed.
The figure shows a graph of the position of a moving object as a function of time. What is the velocity of the object at each of the following times?(a) At t = 1.0 s(b) At t = 2.5 s (c) At t = 4.0 s (d) At t = 5.5 s
(a) 10 m/s (b) 20 m/s (c) 0 m/s (d) -40 m/s
A car with good tires on a dry road can decelerate (slow down) at a steady rate of about 5.0 m/s2 when braking. If a car is initially traveling at 55 mi/h (a) how much time does it take the car to stop?(b) what is its stopping distance?
(a) 4.9 sec (b) 120.49 m
What is 56 + (32.00)/(1.2465 + 3.45) written with the correct number of significant figures?
63
Add and and express your answer in milligrams (mg).
7.05 × 107 mg
The magnitude of the resultant of two vectors cannot be less than the magnitude of either of those two vectors.
False
A rock is thrown from the upper edge of a tall cliff at some angle above the horizontal. It reaches its highest point and starts falling down. Which of the following statements about the rock's motion are true just before it hits the ground? (There could be more than one correct choice.)
Its horizontal velocity component is the same as it was just as it was launched.
Which of the following graphs represent an object at rest? (There could be more than one correct choice.)
Graph A
Which of the following graphs represent an object having zero acceleration?
Graphs a and b
If a tree is 15 m tall, its height expressed in feet is x ft, where x is
Greater than 15
If an operatic aria lasts for 5.75 min, its length expressed in seconds is x s, where x is
Greater than 5.75
If a flower is 6.5 cm wide, its width expressed in millimeters is x mm, where x is
Greater than 6.5
When a ball is thrown straight up with no air resistance, the acceleration at its highest point
Is downward
A ball is thrown straight up, reaches a maximum height, then falls to its initial height. Which of the following statements about the direction of the velocity and acceleration of the ball as it is going up is correct?
Its velocity points upward and its acceleration points downward.
James and John dive from an overhang into the lake below. James simply drops straight down from the edge. John takes a running start and jumps with an initial horizontal velocity of 25 m/s. Compare the time it takes each to reach the lake below if there is no air resistance.
James and John will reach the surface of the lake at the same time.
If a woman weighs 125 lb, her mass expressed in kilograms is x kg, where x is
Less than 125
If the velocity of an object is zero at one instant, what is true about the acceleration of that object? (There could be more than one correct choice.)
The acceleration could be positive. The acceleration could be negative. The acceleration could be zero.
A rock from a volcanic eruption is launched straight up into the air with no appreciable air resistance. Which one of the following statements about this rock while it is in the air is correct?
The acceleration is downward at all points in the motion.
When adding 350 to 0.23
The answer would be 350
A ball is thrown horizontally from the top of a tower at the same instant that a stone is dropped vertically. Which object is traveling faster when it hits the level ground below if neither of them experiences any air resistance?
The ball
If the velocity versus time graph of an object is a straight line making an angle of +30° (counter clockwise) with the time axis, the object is
moving with constant non-zero acceleration.
The current definition of the standard second of time is based on
the frequency of radiation emitted by cesium atoms.
