Honors Physics Midterm
Circle the significant figures in 40.60
(40.60)
A vector in the xy-plane has an x-component of -7.50 units. What must be the y-component of this vector so that its magnitude is 10.0 units? (Note: There are two possible answers.)
+6.61 units, -6.61 units
An air-filled balloon with a mass of 3.0 g is placed in a pool of water. What is the magnitude of the buoyant force acting on the balloon is the density of air is 1.29∙10⁻³ g/cm³ and the density of water is 1.00 g/cm³ ?
0.0 29 N
Circle the significant figures in 0.050200
0.0(50200)
A raft with a length of 3.0 m, a width of 1.5 m, a thickness of 0.12 m, and a density of 750.0 kg/m³ is placed in a river. How far below the water's surface does the bottom of the raft sink? (Recall that fresh water has a density of 1.00∙10³ kg/m³.)
0.09 m
The graph in the figure represents the velocity of a particle as it travels along the x-axis. What is the average acceleration of the particle between t=2.0 s and t=4.0 s?
1.5 m/s²
The established value for the speed of light in a vacuum is 299,792,458 m/s. What is the order-of-magnitude of this number?
10⁸
A bucket filled with water has a mass of 23 kg and is attached to a rope wound around a cylinder with a radius of 0.050 m at the top of a well. What torque does the weight of the water and the bucket produce on the cylinder? (g=9.81 m/s²)
11 N∙m
A 590 kg rocket is at rest on the launch pad. What upward thrust force is needed to accelerate the rocket uniformly to an upward speed of 28 m/s in 3.3 s?
11,000 N
Two snowballs with masses of 0.48 kg and 0.81, respectively, collide head on and combine to form a single snowball. The initial speed for each is 14 m/s. If the velocity of the new combined snowball is 2.4 m/s after the collision, what is the decrease in kinetic energy?
120 J
Calculate the following, expressing the answer in scientific notation with the correct number of significant figures: (8.86+1.0∙10⁻³)/(3.610∙10⁻³)
2.45∙10³
The absolute pressure below the surface of a freshwater lake is 3.51∙10⁵ Pa. At what depth does this pressure occur? Assume that atmospheric pressure is 1.01∙10⁵ Pa and the density of the water is 1.00∙10³ kg/m³.
25.5 m
What is the average power output of a weightlifter who can lift 250 kg a height of 2.0 m in 2.0 s?
2500 W
A small airplane flies at a velocity of 145 km/h towards the south as observed by a person on the ground. The airplane pilot measures an air velocity of 172 km/h south. What is the velocity of the wind that affects the plane?
27 km/h south
Old Faithful geyser in Yellowstone National Park shoots water every hour to a height of 40.0 m. With what velocity does the water leave the ground?
28.0 m/s
A girl pushes a box that has a mass of 450 N up an incline. If the girl exerts a force of 150 N along the incline, what is the mechanical advantage of the incline?
3.0
A flatbed truck is carrying an 800 kg load of timber that is not tied down. The maximum friction force between the truck bed and the load is 2400 N. What is the greatest acceleration that the truck can have without losing its load?
3.00 m/s² forward
Suppose a certain type of deciduous tree releases 7500 leaves on average each fall. If the average mass of each leaf is 1.7 g, and a 135,000 acre forest has 206 of these trees per acre, how many kilograms of leaved are dropped on the forest each fall? Express the answer in scientific notation and with the correct number of significant digits.
3.5∙10⁸ kg
An elevator weighing 2.58∙10⁵ N is supported by a steel cable. What is the tension (force) in the cable when the elevator is accelerated upward at a rate of 3.33 m/s²? (g=9.81 m/s²)
346,000 N
A worker pushes a box with a horizontal force of 50.0 N over a level distance of 5.0 m. If a frictional force of 43 N acts on the box in a direction opposite to that of the worker, what net work is done on the box?
35 J
Vector A is 3.2 m in length and points along the positive y-axis. Vector B is 4.6 m in length and points along a direction 195° counterclockwise from the positive x-axis. What is the magnitude and direction of the resultant when vectors A and B are added?
4.8 m at 24°above negative x-axis.
A force of 1250N is needed to move a crate weighing 3270 N up a ramp that is 4.55 m long. If the elevated end of the ramp is 0.750 m high, what is the efficiency of the ramp?
43.1%
What velocity must a 1120 kg car have in order to have the same momentum as a 3360 kg truck traveling at a velocity of 16 m/s to the west?
48 m/s west
A hydraulic lift consists of two pistons that connect to each other by an incompressible fluid. If one piston has an area of 0.15 m² and the other an area of 6.0 m², how large a mass can be raised by a force of 130 N exerted on the smaller piston?
530 kg
A bobsled zips down an ice track, starting from rest at the top of a hill with a vertical height of 150 m. Disregarding friction, what is the velocity of the bobsled at the bottom of the hill? (g=9.81 m/s²)
54 m/s
A baseball bat strikes a baseball with a force of 37 N. The bat is in contact with the ball for 0.19 s. What is the magnitude of the change in momentum of the ball?
7.0 kg∙m/s
Sarah drives at a constant speed of 15 m/s around a circular horizontal curve of diameter 60 m. What are the magnitude and direction of her acceleration?
7.5 m/s² towards the center of the circle
A 2200 kg auto moving northward at 12.0 m/s runs into a 3800 kg truck which is also moving northward, but at 5.00 m/s. If the vehicles lock bumpers, how fast are they moving just after the collision?
7.6 m/s
Convert 8.66∙10⁻⁹m to millimeters using scientific notation.
8.66∙10⁻⁶mm
A batter applies an average force 8000 N to a baseball for 1.1 ms. What is the magnitude of the impulse delivered to the baseball by the bat?
8.8 kg∙m/s
A 5.00∙10² N crate is pushed to the top of a 5.00 m ramp, which is inclined at 20.0° with the horizontal. What is the potential energy of the crate?
855 J
Convert 92∙10³km to decimeters using scientific notation.
9.2x10⁸dm
Two trucks with equal mass attracted to each other with a gravitational force of 6.7∙10⁻⁴ N. The trucks are separated by a distance of 3.0 m. What is the mass of one of the trucks? (G=6.673∙10⁻¹¹N∙m²/kg²)
9500 kg
A horizontal 52 N force is needed to slide a 50 kg box across a flat surface at a constant velocity of 3.5 m/s. What is the coefficient of kinetic friction between the box and the floor?
A. 0.11
A shown in the figure, a given force is applied to a rod in several different ways. In which case is the torque about the pivot P due to this force the greatest? (refer to test)
A. 1
The Aswan High Dam on the Nile River in Egypt is 111 m high. What is the gauge pressure in the water at the foot of the dam? The density of water is 1000 kg/m³.
A. 1.09∙10⁶ Pa
A block of metal weighs 40 N in air and 30 N in water. What is the buoyant force on the block due to the water? The density of water is 1000 kg/m³.
A. 10 N
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. 0.0 m/s D. -40 m/s
An 82 kg painter stands on a long horizontal board 1.55 m from one end. This 27 kg board is uniform, 5.5 m long, and supported on each end by vertical posts. A. What is the magnitude of the total force provided by both posts? B. With what force does the post that is closest to the painter push upward on the board?
A. 1100 N B. 710 N
Two perpendicular forces, one of 45.0 N directed upward and the other of 60.0 N directed to the right, act simultaneously on an object with a mass of 35.0 kg. What is the magnitude of the resultant acceleration of the object?
A. 2.14 m/s²
Calculate the pressure exerted on the ground due to the weight of a 79-kg person standing on one foot if the bottom of the person's foot is 13 cm wide and 28 cm long.
A. 2.1∙10⁴ Pa
The figure shows an object's acceleration-versus-force graph. What is the mass of this object?
A. 2.5 g
A 1200 kg cannon suddenly fires a 100 kg cannonball at 35 m/s. What is the recoil speed of the cannon? Assume that frictional forces are negligible and the cannon is fired horizontally.
A. 2.9 m/s
How much kinetic energy does a 0.30 kg stone have if it is thrown at 44 m/s?
A. 290 J
A projectile is shot horizontally at 23.4 m/s from the roof of a building 55 m tall and experiences negligible air resistance. A. Determine the time necessary for the projectile to reach the ground below. B. Determine the distance from the base of the building that the projectile lands. C. Determine the horizontal and vertical components of the velocity just before the projectile reaches the ground.
A. 3.35 s B. 78.4 m C. Horizontal: 23.4 m Vertical: 33 m
Calculate the following, and express the answer in scientific notation with the correct number of significant figures: (0.82+0.042)(4.4x10³)
A. 3.8x10³
The lug nuts on a car wheel require tightening to a torque of 90 N∙m. If a 30 cm long wrench is used, what is the magnitude of the minimum force required using the wrench?
A. 300 N
According to legend, to determine whether the king's crown was made of pure gold, Archimedes measured the crown's volume by determining how much water it displaced. The density of gold is 19.3 g/cm³. If the crown's mass was 6.00x10² g, what volume of water would have been displaced if the crown was indeed made of pure gold?
A. 31.1 cm³
One of the dangers of tornadoes 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 2.03 m on each side? (1.00 atm= 1.01∙10⁵ Pa)
A. 4.59∙10⁴ N
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 (24.6 m/s) a) How much time does it take the car to stop? b) What is its stopping distance?
A. 4.9 s B. 61 m
What is the gravitational force acting on a 59 kg person due to another 59 kg person standing 2.0 m away? We can model each person as a small sphere. (G= 6.67∙10⁻¹¹ N∙m²/kg²)
A. 5.8∙10⁻⁸ N
A block of mass m=3.6 kg, moving on a frictionless surface with a speed v=9.3 m/s, makes a sudden perfectly inelastic collision with a stationary block mass M, as shown in the figure. Just after the collision, the 3.6 kg block recoils with a speed of v=2.7 m/s. What is the speed V of the other block?
A. 6.6 m/s
In a physical fitness program, a woman who weighs 510 N runs up four flights of stairs in 22 s. Each flight rises 3.1 m. (1 hp=746 W) A. What is her total change in potential energy? B. What was the minimum average power (in watts) that she expended during the 22 s? C. What horsepower motor would be required to generate the same power?
A. 6300 J B. 290 W C. 0.39 hp
You walk 33 m to the north, then turn 60° to your right and walk another 45 m. How far are you from where you originally started.
A. 68 m
What is the mass of an object that experiences a gravitational force of 685 N near Earth's surface where g= 9.80 m/s²?
A. 69.9 kg
A child does 350 J of work while pulling a box from the ground up to his tree house at a steady speed with a light rope. The tree house is 4.0 m above the ground. What is the mass of the box?
A. 8.9 kg
A sled weighing 1.0∙10² N is held in place on a frictionless 20.0°slope by a rope attached to a stake at the top. The rope is parallel to the slope. What is the normal force of the slope acting on the sled?
A. 94 N
Four trials of a chemical reaction were completed, and the change in temperature(∆T) was measured every five seconds. Based on the data in the table above, answer the following questions. A. Are there any unexpected or unusual results? Explain your answer. B. What is the general relationship between temperature and time? C. Disregarding any trial(s) with unexpected results, express this relationship in the form of a general equation.
A. During trial 2, the temperature has a higher average than the average temperature in the other trials: while it's still increasing, it does so more rapidly than other trials. Therefore, it's an unusual result compared to the other temperatures at the same time in the other trials. B. The general relationship is a direct relationship: as the time increases, the temperature increases as well. C. ∆C=mt
A truck has four times the mass of a car and is moving with twice the speed of the car. If Kt and Kc refer to the kinetic energies of the truck and car respectively, it is correct to say that
A. Kt=16Kc
A lack of precision in scientific measurements typically arises from
A. Limitations of the measuring instrument
A piece of chalk is dropped by a teacher walking at a speed of 1.5 m/s. From the teacher's perspective, the chalk appears to fall
A. Straight down.
A rubber ball and a lump of clay have equal mass. They are thrown with equal speed against a a wall. The ball bounces back with nearly the same speed with which it hit. The clay sticks to the wall. Which one of these objects experiences the greater momentum change?
A. The ball
What happens when a person blows between two paper cups that are hung by strings 10 cm apart?
A. The cups move towards each other.
Two forces produce equal torques on a door about the door hinge. The first force is applied at the midpoint of the door; the second force is applied at the doorknob. Both forces are applied perpendicular to the door. Which force has a greater magnitude?
A. The first force (at the midpoint)
A buoyant force acts in the opposite direction of gravity. Therefore, which of the following is true of an object completely submerged in water?
A. The net force on the object is smaller than the weight of the object.
Which of the following has the greatest momentum?
A. a tortoise with a mass of 275 kg moving at a velocity of 0.55 m/s.
In a coordinate system, a vector is oriented at angle X with respect to the x-axis. The x-component of the vector equals the vector's magnitude multiplied by which trigonometric ratio?
A. cos X
As a basketball player starts to jump for a rebound, the player begins to move upward faster and faster until his shows leave the floor. At the moment the player begins to jump, the force of the floor on the shoes is
A. greater than the player's weight.
If the velocity versus time graph of an object is a horizontal line, the object is
A. moving with zero acceleration.
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 (refer to test)
A. perfectly elastic
Which statement about the acceleration of an object is correct?
A. the acceleration of an object is directly proportional to the net external force acting on the object and inversely proportional to the mass of the object.
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 had the greater buoyant force on it?
A. the aluminum
Two cyclists who weigh the same and have identical bicycles rise up the same mountain, both starting at the same time. Joe rides straight up the mountain, and Bob rides up the longer road that has a lower grade. Joe gets to the top before Bob. Ignoring friction and wind resistance, which one of the following statements is true?
A. the amount of work done by Joe is equal to the amount of work done by Bob, but the average power exerted by Joe is greater than that of Bob.
A moderate force will break an egg. Using the concepts of momentum, force, and time interval, explain why an egg is more likely to break when it is dropped on concrete than if it is dropped on grass.
An egg is more likely to break when dropped on concrete than on grass because when an egg is dropped on concrete, there is a large force being exerted on it in a short time interval, forcing it to rest more quickly and making it more likely to break. In contrast, if it lands on grass, the eggs will have a lesser force exerted on it for a longer period of time, making it less likely to break because the momentum decreases.
Which of the following quantities had units of a velocity? (There could be more than one correct choice.)
B. -120 m/s E. 9.8 m/s downward
A 40 kg box is being pushed along a horizontal smooth surface. The pushing force is 15 N directed at an angle of 15° below the horizontal. What is the magnitude of the acceleration of the crate?
B. 0.36 m/s²
A 0.14 kg baseball is dropped from rest from a height of 2.0 m above the ground. What is the magnitude of its momentum just before it hits the ground if we neglect air resistance?
B. 0.88 kg∙m/s
If a net force accelerates a 4.5 kg tool at 40 m/s², what acceleration would that same net force give to an 18 kg tool?
B. 10 m/s²
Estimate the order of magnitude of the length of a football field.
B. 10² m
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. How far is your hometown from school?
B. 190 mi
How much elastic potential energy is stored in a bungee cord with a spring constant of 10.0 N/m when the cord is stretched 2.00 m?
B. 20.0 J
A horizontal force of 200 N is applied to move a 55 kg television set across a 10 m level surface. What is the work done by the 200 N force on the television set?
B. 2000 J
A 0.50 kg toy is attached to the end of a 1.0 m very light string. The toy is whirled in a horizontal circular path on a frictionless tabletop. If the maximum tension that the string can withstand without breaking is 350 N. What is the maximum speed the mass can have without breaking the string?
B. 26 m/s
A 10 kg mass, hung by an ideal spring, causes the spring to stretch 2.0 cm. What is the spring constant (force constant) for this spring?
B. 49 N/cm
A ball is thrown straight up with a speed of 36 m/s. How long does it take to return to its starting point, assuming negligible air resistance?
B. 7.3 s
At what minimum rate is a 60.0 kg boy using energy when, in 8.00 s, he runs up a flight of stairs that is 10.0 m high?
B. 735 W
A 15 kg child is sitting on a playground teeter-totter, 1.5 m from the pivot. What is the magnitude of the minimum force, applied 0.30 m on the other side of the pivot, that is needed to make the child lift off the ground?
B. 740 N
An athlete competing in the long jump leaves the ground with a speed of 9.14 m/s at an angle of 55° with the vertical. What is the length of the athlete's jump if air resistance is of no significance?
B. 8.0 m
Which of the following statement is not correct?
B. A fluid has a definite shape
Human reaction time is usually greater than 0.10 s. If your friend holds a ruler between your fingers and releases it without warning, how far can you expect the ruler to fall before you catch it, assuming negligible air resistance?
B. At least 4.9 cm
At what point of the ball's path shown in the figure above is the vertical component of the ball's velocity zero? (refer to test)
B. B
Tides are caused by
B. Differences in the gravitational force of the moon at different points on Earth.
A 20-tun truck collides with a 1500 lb car. Which of the following statements must be true?
B. During the collision, the force on the truck is equal to the force on the car.
In the figure, what does the spring scale read? the pulleys are ideal and the strings and scale are also massless.
B. Exactly 1.0 N
A box is placed on a table which rests on the floor. The box pushes on the table; the reaction force to the box's push on the table is the table's push on the floor.
B. False
A roller coaster climbs up a hill at 4 m/s and then zips down the hill at 30 m/s. The momentum of the roller coaster
B. Is greater down the hill than up the hill.
Which of the following is an area of physics that studies motion and its causes?
B. Mechanics
Which of the following is always true?
B. Pressure always increases when force increases or the area acted on decreases.
A more powerful motor can do
B. The same work in a shorter time interval.
A pilot drops a package from a plane flying horizontally at a constant speed. Neglecting air resistance, when the package hits the ground the horizontal location of the plane will
B. be directly over the package.
Two displacement vectors have magnitudes of 5.0 m and 7.0 m, respectively. If these two vectors are added together, the magnitude of the sum
B. could be as small as 2.0 m or as large as 12 m.
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 settles to the bottom,
B. falls
Where should a force be applied on a lever arm to produce the most torque?
B. farthest from the axis of rotation
What kind of force provides the centripetal force on the bicycle?
B. friction
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,
B. increases as it nears the Sun.
Which of the following is the tendency of an object to maintain its state of motion?
B. inertia
When a ball is thrown straight up with no air resistance, the acceleration at its highest point
B. is downward
A force does work on an object if the component of the force
B. is parallel to the displacement of the object.
The main difference between kinetic energy and potential energy is that
B. kinetic energy involves motion, and potential energy involves position.
Salt water is denser than fresh water. A ship floats in both fresh water and salt water. Compared to the fresh water, the volume of water displaced in the salt water is
B. less
A person who normally weighs 700 N is riding in an elevator that is moving upward but slowing down at a steady rate. If this person is standing on a bathroom scale inside the elevator, what would the scale read?
B. less than 700 N.
The symbol mm represents
B. millimeter
Which of the following statements about the conservation of momentum is not correct?
B. momentum is not conserved for a system of objects in a head-on collision.
Which of the following expressions gives units of kg∙m²/s²?
B. m∙(∆x)²/(∆t)²
Three values were obtained for the mass of a metal bar: 8.83 g; 8.84 g; 8.82 g. The known mass is 10.68 g. The values are
B. precise
For general projectile motion with no air resistance, the horizontal component of a projectile's velocity
B. remains a non-zero constant.
For general projectile motion with no air resistance, the vertical component of a projectile's acceleration
B. remains a non-zero constant.
You are in a train traveling on a horizontal track and notice that a piece of luggage starts to slide directly toward the front of the train. From this observation, you can conclude that this train is
B. slowing down
When you blow some air above a paper strip, the paper rises. This happens because
B. the air above the paper moves faster and pressure is lower
Which of the following occurs to a person standing near the edge of a railroad track when a high-speed train passes?
B. the person tends to be pulled towards the train.
A rocket explodes into two fragments, one 25 times heavier than the other. The magnitude of the momentum change of the lighter fragment is
B. the same as the momentum change of the heavier fragment
A 50.0 kg crate is being pulled along a horizontal smooth surface. The pulling force is 10.0 N and is directed 20.0°above the horizontal. What is the magnitude of the acceleration of the crate?
B.0.188 m/s²
To determine the height of a bridge above the water, a person drops a stone and measures the time it takes for it to hit the water. If the time is 2.3 s, what is the height of the bridge? Neglect air resistance.
C. 26 m
A 3.00 kg toy falls from a height of 1.00 m. What will the kinetic energy of the toy be just before the toy hits the ground? (assume no air resistance and that g=9.81 m/s².)
C. 29.4 J
If the air pressure in a tire is measured as 2.0x10⁵ Pa, and atmospheric pressure equals 1.0x10⁵ Pa, what pressure does the air within the tire exert outward on the tire walls?
C. 3.0x10⁵
A runner ran a marathon (approximately 42.0 km) in 2 hours and 57 min. What was the average speed of the runner in m/s?
C. 3.95 m/s
What magnitude net force is required to accelerate a 1200 kg car uniformly from 0 m/s to 27.0 m/s in 10.0 s?
C. 3240 N
A tiger is running in a straight line. If we double both the mass and speed of the tiger, the magnitude of its momentum will increase by what factor?
C. 4
An airplane increases its speed at the average rate of 15 m/s². How much time does it take to increase its speed from 100 m/s to 160 m/s?
C. 4.0 s
A man in a gym is holding a 8.0 kg weight at arm's length, a distance of 0.55 from his shoulder joint. What is the torque about his shoulder joint due to the weight if his arm is horizontal?
C. 43 N∙m
A car travels at 15 m/s for 10 s. It then speeds up with a constant acceleration of 2.0 m/s² for 15 s. As the end of this time, what is its velocity?
C. 45 m/s
Astronaut Jennifer's lifeline to her spaceship comes loose and she finds herself stranded, floating 100 m from the mothership. She suddenly throws her 2.00 kg wrench at 20 m/s in a direction away from the ship. If she and her spacesuit have a combined mass of 200 kg, how long does it take her to coast back to her spaceship?
C. 500 s
Matthew pulls his little sister Sarah along the horizontal ground in a wagon. He exerts a force on the wagon of 60.0 N at an angle of 37.0° above the horizontal. If he pulls her a distance of 12.0 m, how much work does Matthew do?
C. 575 J
Vector A has a magnitude of 6.0 m and points 30° north of east. Vector B has a magnitude of 4.0 m and points 30° west of north. The resultant vector A+B is given by
C. 7.2 m at an angle of 26° east of north.
What kind of simple machine are you using if you pry a nail from a board with the back of a hammer?
C. A lever
An object is moving with a constant non-zero velocity in the +x direction. The position versus time graph of this object is
C. A straight line making an angle with the time axis.
The slope of a velocity versus time graph gives
C. Acceleration
If the position versus time graph of an object is a horizontal line, the object is
C. At rest
According to the scientific method, how does a physicist formulate and objectively test hypotheses?
C. By experiments
What is the term for the net force directed toward the center of an object's circular path?
C. Centripetal force
Which of the following forces arises from direct physical contact between two objects?
C. Contact force
A hiker uses a compass to navigate through the woods. Identify the area of physics that this involves.
C. Electromagnetism
The length of a force vector represents the
C. Magnitude of the force
In which of the following sentences is work used in the scientific sense of the word?
C. Sam and Rachel pushed hard, but they could do no work on the car.
If an object is only partially submerged in a fluid, which of the following is correct?
C. The density of the fluid is greater than the density of the object.
Suppose that an object travels from one point in space to another. Make a comparison between the magnitude of the displacement and and the distance travelled by this object.
C. The displacement is either less than or equal to the distance travelled.
A small car meshes with a large truck in a hear-on collision. Which of the following statements concerning the magnitude of the momentum change during the collision is correct?
C. The small car and the truck experience the same magnitude momentum change.
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?
C. They are traveling at the same speed.
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?
C. To allow the force of the expanding gases from the gunpowder to act for a longer time.
When is the average velocity of an object equal to the instantaneous velocity?
C. When the velocity is constant.
A free-body diagram of a ball falling in the presence of air resistance would show
C. a downward arrow to represent the force due to gravity and an upward arrow to represent the force of air resistance.
Is a force is exerted on an object, which statement is true?
C. a small force applied over a long time interval can produce a large change in the object's momentum.
If a nonzero net force is acting on an object, then the object is definitely
C. being accelerated
A free-body diagram represents all of the following except
C. forces exerted by the object.
Which of the following is a form of mechanical energy?
C. gravitational potential energy
The momentum of an isolated system is conserved
C. in both inelastic and elastic collisions
Friction converts kinetic energy to
C. non-mechanical energy
For incompressible fluids, density changes little with changes in
C. pressure
A wooden block contains some nails so that its density is exactly equal to that of water. If it is placed in a tank of water and released from rest when it is completely submerged, it will
C. remain where it is released.
When comparing the momentum of two moving objects, which of the following is correct?
C. the less massive object will have less momentum if the velocities are the same.
Why does the lift on an airplane wing increase as the speed of the airplane increases?
C. the pressure above the wing becomes less than the pressure below the wing.
An object moves in a circular path at a constant speed. Compare the direction of the object's velocity and acceleration vectors.
C. the vectors are perpendicular to each other.
The x-component of vector A is 8.7 units, and its y-component is -6.5 units. The magnitude of A is closest to
D. 11 units
A sled traveling at a speed of 3.0 m/s slows to a stop 4.0 m from the point where its passenger rolled off. What is the magnitude of the horizontal net force that slows the 110 N sled? (Assume Ag= 9.81 m/s².)
D. 13 N
A car is moving with a speed of 32.0 m/s. The driver sees an accident ahead and slams on the brakes, causing the car to slow down with a uniform acceleration of magnitude 3.50 m/s². How far does the car travel after the driver puts on the brakes until it comes to a stop?
D. 146 m
The sum of two vectors of fixed magnitude has its minimum magnitude when the angle between these vectors is
D. 180°
Find the resultant of these two vectors: 2.00∙10² units due east and 4.00∙10² units 30.0° north of west.
D. 248 units, 53.9° north of west
How much power is required to lift a 2.0 kg mass at a speed of 2.0 m/s?
D. 39 W
Calculate the following, and express the answer in scientific notation with the correct number of significant figures: 21.4+15+17.17+4.003
D. 5.8x10¹
A ball with a momentum of 4.0 kg∙m/s hits a wall and bounces straight back without losing any kinetic energy. What is the change in the ball's momentum?
D. 8.0 kg∙m/s
Which of the following situations represents a negative displacement? (Assume positive position is measured vertically upward along a y-axis.)
D. A cat jumps from a tree limb to the ground.
Which form of energy is involved in weighing fruit on a spring scale?
D. Elastic potential energy.
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?
D. F
What causes a moving object to change direction?
D. Force
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
D. In a general northwesterly direction.
If a satellite moves with constant speed in a perfectly circular orbit around the earth, what is the direction of the acceleration of the satellite?
D. Inward toward the earth.
An object moving in the +x direction experiences an acceleration of +2.0 m/s². This means the object
D. Is increasing its velocity by 2.0 m/s every second.
A spaceship is traveling to the moon. At what point is it beyond the pull of Earth's gravity?
D. It is never beyond the pull of Earth gravity.
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 answer.)
D. Its horizontal velocity component is the same as it was just as it launched.
Which of the following statements about floating objects is correct?
D. The buoyant force equals the object's weight.
The free-body diagram shown above represents a car being pulled by a towing cable. In the diagram, the 5800 N force is
D. The force exerted by the towing cable on the car.
Which of the following quantities measures the ability of a force to rotate or accelerate an object around an axis?
D. Torque
Which of the following is a true statement about the conservation of energy?
D. Total energy is always conserved.
An astronaut goes out for a 'space-walk' at a distance above the earth equal to the radius of the earth. What is her acceleration due to gravity at that point?
D. g/2
In the figure above, according to Kepler's laws of planetary motion,
D. if ∆t₁=∆t₂, then A₁=A₂
When a car makes a sharp left turn, what causes the passengers to move towards the right side of the car?
D. inertia
An object is moving with constant non-zero velocity. Which of the following statements about it must be true?
D. the net force on the object is zero.
An object of mass m rests on a flat table. The earth pulls on this object with a force of magnitude mg. What is the reaction force to this pull?
D. the object pulling upward on the Earth with force mg.
As an object falls toward Earth,
D. the upward acceleration of Earth is negligible because of its large mass.
Which of the following is not a fluid?
D. wood
Which of the following equations best describes the graph above?
D. y=0.5x
Three vectors, S, T, and U, have the components shown in the table. What is the magnitude of the resultant of these three vectors? S: X-component: 3.50 m, Y-component: -4.50 m T: X-component: 2.00 m, Y-component: 0.00 m U: X-component: -5.50 m, Y-component: 2.50 m
E. 2.00 m
Consider a brick that is totally immersed in water, with the long edge of the brick vertical. The pressure on the brick is
E. greatest on the bottom of the brick.
Which of the following statements are true about an object in two-dimensional projectile motion with no air resistance? (There could be more than one correct choice.)
E. the horizontal acceleration is always zero and the vertical acceleration is always a non-zero constant downward.
As shown in the figure(see Ch. 8 test), fluid fills a container having several sections. At which of the indicated points is the pressure greatest?
E. the pressure is the same at each of the labelled points.
When a car is moving, what happens to the velocity and acceleration of the car if the air resistance becomes equal to the force acting in the opposite direction?
If the forces become equal, then the car will be going at a constant velocity where the net force is zero and the acceleration is zero as well.
Using the data above, construct a graph of the time require to make a trip 100 km measured at various speeds. What kind of relationship does the graph illustrate?
Inverse relationship
Why is the base of a dam thicker than the top part of the dam?
It's thicker because as the depth of the water increases, so does the pressure. Therefore, the bottom part of the dam has to withstand more pressure, and that's why it's thicker.
What are the SI base units for length, mass, and time?
Length: meters Mass: kilogram Time: seconds
Compare the gravitational force the sun exerts on Earth to the gravitational force Earth exerts on the sun.
The gravitational force exerted on the Sun by Earth is equal and opposite to the gravitational force exerted on Earth by the sun.
When a horse pulls on a cart, the cart pulls on the horse with an equal but opposite force. How is the horse able to pull the cart?
The horse would be able to pull the cart because the horse also pushes its hooves into the ground with a force, and the ground also pushes back on the horse and makes the cart move as well.
Two horses are side by side on a carousel. Which has a greater tangential speed- the one closer to the center or the one farther from the center? Explain.
The one further from the center would have the greater tangential speed because it would have to complete one rotation in the same amount of time as the one closer to the axis of rotation, so since it has a greater distance to cover than the other horse, it would have a greater tangential speed.
A student walks to class at a velocity of 3 m/s. To avoid walking into a door as it opens, the student slows to a velocity of 0.5 m/s. Now late for class, the student runs down the corridor at a velocity of 7 m/s. At what point in this scenario does the student have the least momentum?
The point when the student's velocity is 0.5 m/s.
How does the use of a machine alter the work done on the object?
The use of a machine doesn't affect the total work done on an object, the work done is still the same, however, it does affect how much force you can exert on an object over a period of time: it could decrease a force you exert but require you to exert over a longer period.
