Physics Final
A boy throws a rock with an initial velocity of 3.13 m/s at 30.0° above the horizontal. How long does it take for the rock to reach the maximum height of its trajectory if air resistance is negligibly small and g = 9.80 m/s2?
0.15 sec
a 50kg crate is being pulled along a horizontal smooth surface. the pulling force is 10N and is directly 20 degrees above the horizontal. what is the acceleration of the crate?
0.188m/s2
A 4.0-m-long ladder leans against a wall at an angle of 48° with respect to the floor. Asssume that friction between the ladder and the wall is negligible.What is the minimum value of μs, the coefficient of static friction with the ground, which will prevent the ladder from slipping?
0.25
A 2-m-long board weighing 50 N extends out over the edge of a table, with 40% of the board's length off the table. How far beyond the table edge can a 25-N cat walk before the board begins to tilt?
0.4
An airplane needs to reach a forward velocity of 203.0 km/h to take off. On a 2000-m runway, what is the minimum uniform acceleration necessary for the plane to take flight if it starts from rest?
0.795 m/s^2
A 14,000-kg boxcar is coasting at 1.50 m/s along a horizontal track when it suddenly hits and couples with a stationary 10,000-kg boxcar. What is the speed of the cars just after the collision?
0.875 m/s
the innermost satellite of jupiter orbits the planet with a radius of 4.22x10^3 km and a period of 1.77 days. what is the mass of jupiter?
1.89x10^27
a 6kg box slides down an inclined plane that makes an angle of 39 degrees with the horizontal . if the coefficient of kinetic friction is 0.4 at what rate does the box accelerate down the slope?
1.9m/s2
A hypothetical planet has a mass of half that of the Earth and a radius of twice that of the Earth. What is the acceleration due to gravity on the planet in terms of g, the acceleration due to gravity at the Earth?
1/8
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 13.2 m, 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.
11.28 m/s
a roller coaster contains a loop the loop in which the car and rider are completely upside down. if the radius of the loop is 13.2m, with what minimum speed must the car traverse the loop so loop so that the rider does not fall out while upside down at the top? assume the rider is not strapped to the car
11.4m/s
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
11.541 kg
A cart starts from rest and accelerates uniformly at 4.0 m/s2 for 5.0 s. It next maintains the velocity it has reached for 10 s. Then it slows down at a steady rate of 2.0 m/s2 for 4.0 s. What is the final speed of the car?
12 m/s
a 200N sled of slides down a frictionless hillside that rises at 37 degrees above the horizontal. what is the magnitude of the force that the hill exerts on the sled parallel to the surface of the hill?
120N
An airplane with an airspeed of 140 km/h has a heading of 50° west of north in a wind that is blowing toward the east at 25 km/h. What is the groundspeed of the plane?
125.4 km/hr
The components of vectors A and B are given as follows: Ax = 7.6 Bx = -5.1 Ay = -9.2 By = -6.8 What is the magnitude of the vector difference A- B ?
13
A force acts on an object, causing it to move parallel to the force. The graph in the figure shows this force as a function of the position of the object. How much work does the force do as the object moves from 4 m to 6 m?
20 J
A 5.0-N projectile leaves the ground with a kinetic energy of 220 J. At the highest point in its trajectory, its kinetic energy is 120 J. To what vertical height, relative to its launch point, did it rise if there was no air resistance?
20 m
With Conservative Forces: 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)
22 m/s
A lab assistant drops a 400.0-g piece of metal at 100.0°C into a 100.0-g aluminum cup containing 500.0 g of water at In a few minutes, she measures the final temperature of the system to be 40.0°C. What is the specific heat of the 400.0-g piece of metal, assuming that no significant heat is exchanged with the surroundings? The specific heat of this aluminum is 900.0 J/kg ∙ K and that of water is 4186 J/kg ∙ K.
2270 J/kg-K
A 40.0-L container is divided into two equal parts by a rubber membrane. One half of the container has 1.50 moles of an ideal monatomic gas at 250 K, and the other half is a vacuum. The container is well insulated, so there is no exchange of heat with the surroundings. The membrane breaks, and eventually the gas reaches a new equilibrium condition occupying the entire volume. What is the final temperature of the gas?
250 K
A 60-kg skier starts from rest from the top of a 50-m high slope. If the work done by friction is -6.0 kJ, what is the speed of the skier on reaching the bottom of the slope?
28 m/s
A solid steel column is 4.0 m long and 0.20 m in diameter. Young's modulus for this steel is 2.0 × 1011 N/m2. By what distance does the column shrink when a 5000-kg truck is supported by it?
3.12 x 10^-5 m
You want to store 1000 J of energy in an ideal spring when it is compressed by only 2.5 cm. What should be the force constant (spring constant) of this spring?
3.2 x 10^6 m/m
A 5.00-g lead BB moving at 44.0 m/s penetrates a wood block and comes to rest inside the block. If half of its kinetic energy is absorbed by the BB, what is the change in the temperature of the BB? The specific heat of lead is 128 J/kg ∙ K.
3.78 degrees
a flatbed truck is carrying a 20kg crate along a level road. the coefficient of static friction between the caret and the bed is 0.4 and the coeffeicient of kientic friction is 0.3. what is the max acceleration that the truck can have if the crate is to stay in place relative to the truck?
3.92m/s2
A cylinder of gas has a frictionless but tightly sealed piston of mass M. The gas temperature is increased from an initial 27°C to a final 127°C. If the initial volume of the gas in the cylinder is 300 liters, what is the final volume assuming the pressure remains constant
400 L
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 × J/kg, and its specific heat capacity is 4186 J/kg ∙ K.
429 g
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 horizontal?
43.12 N-m
a ferris wheel has radius 5.0m and makes one revolution in 8.0sec. a person weighing 670N is sitting on one of the benches attached at the rim of the wheel. what is the apparent weight (the normal force exerted on her by the bench) of the person as she passes through the highest point of her motion
459N
A laser is thrown upward with a speed of 12 m/s on the surface of planet X where the acceleration due to gravity is 1.5 m/s2 and there is no atmosphere. What is the maximum height reached by the laser?
48 m
The ocean thermal energy conversion project uses the surface water near tropical islands with a temperature of 20°C as the hot temperature reservoir, and the water at some depth, with a temperature of 5.0°C, as the cold temperature reservoir for a heat engine. What is the maximum possible efficiency of an engine running between those two temperatures?
5.1%
An incompressible ideal fluid flows steadily through a pipe that has a change in diameter. The fluid speed at a location where the pipe diameter is 8.0 cm is 1.28 m/s. What is the fluid speed at a location where the diameter has narrowed to 4.0 cm?
5.2 m/s
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
The figure shows a block of mass M hanging at rest. The light wire fastened to the wall is horizontal and has a tension of 38 N. The wire fastened to the ceiling is also very light, has a tension of and makes an angle θ with the ceiling. Find the angle θ.
50 degrees
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 m
A super dart of mass 20 g, traveling at 350 m/s, strikes a steel plate at an angle of 30° with the plane of the plate, as shown in the figure. It bounces off the plate at the same angle but at a speed of 320 m/s. What is the magnitude of the impulse that the plate gives to the bullet?
6.7 N
You drive 6.0 km at 50 km/h and then another 6.0 km at 90 km/h. Your average speed over the 12 km drive will be
64.28 m/s
a 1100kg car traveling at 27m/s starts to decelerate and comes to a complete stop after 578m. what is the average braking force cting on the car?
694N
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/s^2 direction: towards center
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?
736 W
at a given point above earth's surface the acceleration due to the gravity is equal to 7.8m/s2. what is the altitude of this point aboves earth surface?
765009.0165m
a car moving at a steady 10m/s on a level highway encounters a depression that has a circular cross section with a radius of 30m. The car maintains its speed as it drives through the depression. what is the normal force exerted by the seat of the car on a 60kg passenger when the car is at the bottom of the depression?
790N
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. what is the magnitude of the acceleration of the child?
8.05m/s/s
A child sits on a merry-go-round, 1.5 meters from the center. The merry-go-round is turning at a constant rate, and the child is observed to have a radial acceleration of 2.3 m/s2. How long does it take for the merry-go-round to make one revolution?
8.8 seconds
the coeffecients of static and kinetic friction between a 3kg box and a horizontal desktop are 0.4 and 0.3 respectively, what is the force of friction on the box when a 15N horizontal push is applied to the box?
8.82N
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?
8.9 kg
The figure shows a graph of the velocity of an object as a function of time. What is the displacement of the object from 0 s to 6.0 s?
80 m
A girl of mass 55 kg throws a ball of mass 0.80 kg against a wall. The ball strikes the wall horizontally with a speed of 25 m/s, and it bounces back with this same speed. The ball is in contact with the wall 0.050 s. What is the magnitude of the average force exerted on the wall by the ball?
800 N
what is the angular speed in rad/s of a flywheel turning at 813.0 rpm?
85.14rad/s
A jet plane flying 600 m/s experiences an acceleration of 4.0 g when pulling out of the circular section of a dive. What is the radius of curvature of this section of the dive?
9200m
The Moon is 3.84 × 108 m from Earth and takes 27.3 days to complete each orbit. What are the magnitude and direction of the acceleration of the Moon, assuming a circular orbit?
963.16 m 30 degrees
A wire of diameter 0.20 mm stretches by 0.20% when a 6.28-N force is applied to it. What is Young's modulus for this wire?
99.9 x 10^5 N/m^2
An air bubble underwater has the same pressure as that of the surrounding water. As the air bubble rises toward the surface (and its temperature remains constant), the volume of the air bubble
increases
You slam on the brakes of your car in a panic, and skid a certain distance on a straight level road. If you had been traveling twice as fast, what distance would the car have skidded, under the same conditions?
it will skid four times farther
A rubber ball and a lump of clay have equal mass. They are thrown with equal speed against 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?
the rubber ball
a satellite is in the orbit around the earth. which one feels the greater force?
the satellite
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
they will both have the same splashdown speed
When is the average velocity of an object equal to the instantaneous velocity?
where the acceleration is zero
You throw a baseball straight up. Compare the sign of the work done by gravity while the ball goes up with the sign of the work done by gravity while it goes down.
work is negative on the way up and positive on the way down
A race car traveling at a constant speed of 50 m/s drives around a circular track that is 500 m in diameter. What is the magnitude of the acceleration of the car?
10 m/s^2
A hammer is thrown upward with a speed of 14 m/s on the surface of planet X where the acceleration due to gravity is 3.5 m/s2 and there is no atmosphere. What is the speed of the hammer after 8.0 s?
-14 m/sec
During an isothermal process, 5.0 J of heat is removed from an ideal gas. What is the change in internal (thermal) energy of the gas?
-5.0 J
An external heat source supplies heat to a system at a rate of 187 W as the system does work at a rate of 131 W. At what rate is the internal (thermal) energy of the system changing?
-56 W
The graph in the figure shows the x component F of the net force that acts for 10 s on a 100-kg crate. What is the change in the momentum of the crate during the 10 s that this force acts?
-75 kgm/s
A 0.140-kg baseball is thrown with a velocity of 27.1 m/s. It is struck by the bat with an average force of 5000 N, which results in a velocity of 37.0 m/s in the opposite direction from the original velocity. How long were the bat and ball in contact?
.0018 s
During an isothermal process, 5.0 J of heat is removed from an ideal gas. What is the change in internal (thermal) energy of the gas?
0 J
The last page of a book is numbered 764. The book is 3.0 cm thick, not including its covers. What is the average thickness (in centimeters) of a page in the book, rounded to the proper number of significant figures?
0.0079 cm
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 towards the right
a horizontal 52N force is needed to slide a 50kg box across a flat surface at a constant velocity of 3.5m/s. what is the coefficient between the box and the floor?
0.11
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 45kg person steps on a scale in an elevator. the scale reads 460N. what is the magnitude of the acceleration of the elevator?
0.422m/s2
a fan is turned off and its angular speed decreases from 10.0rad/s to 6.3rad/s in 5.0s. what is the magnitude of the angular acceleration of the fan?
0.74rad/sec^2
An airplane needs to reach a forward velocity of 203.0 km/h to take off. On a 2000-m runway, what is the minimum uniform acceleration necessary for the plane to take flight if it starts from rest?`
0.795 m/s^2
at thier closest approach, venus and earth are .2x10^10 m apart. the mass of venus is4.87x10^24kg, the mass of earth is 5.97x10^24 kg. what is the magnitude of the graviational force exerted by venus on earth at that point?
1.1x10^18N
The coefficient of linear expansion of steel is 12 × 10-6 K-1. What is the change in length of a 25-m steel bridge span when it undergoes a temperature change of 40 K from winter to summer?
1.2 cm
A cylinder of gas has a frictionless but tightly sealed piston of mass M. The gas temperature is increased from an initial 27°C to a final 127°C. If the initial volume of the gas in the cylinder is 300 liters, what is the final volume assuming the pressure remains constant
1.33
Two vehicles approach a right angle intersection and then suddenly collide. After the collision, they become entangled. If their mass ratios were 1:4 and their respective speeds as they approached the intersection were both 13 m/s, find the magnitude and direction of the final velocity of the wreck.
10.72 (magnitude), 75.96 degrees (direction)
starting from rest a wheel with constant angular acceleration turns through an angle of 25 rad in a time t. through what angle will it have turned after time 2t?
100 radian
A train travels at a constant speed of 60.4 mi/h for 101.5 min. What distance does the train cover expressed to the correct number of significant figures?
102 mi
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 ΔT, the change in temperature of Object 2 will be
12
A plastic block of dimensions 2.00 cm × 3.00 cm × 4.00 cm has a mass of 30.0 g. What is its density?
1250 kg/m^3
a small 175g ball on the end of a light string is revolving uniformly on a frictionless surface in a horizontal diameter of 1.0m. the ball makes 2.0revolutions every 1.0s. what are the magnitude and direction of the acceleration of the ball? what is the tension in the string?
13.817m/s^2 towards center of rotation tension = 2.418N
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.
1333 kg/m^3
the figure shows an acceleration versus force graph for 3 objects pulled by rubber bands. the mass of object 2 is 36kg. what are the masses of objects 1 and 3?
14kg and 90kg
A rubber ball experiences the force shown in below as it bounces off the floor. What is the average force on the ball?
150 N
A plane has an eastward heading with an airspeed of 156 m/s. A 20.0 m/s wind is blowing southward at the same time as the plane is flying. The velocity of the plane relative to the ground is
157 m/s 7.31 degrees SE
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 child pulls on a wagon with a force of 75 N. If the wagon moves a total of 42 m in 3.1 min, what is the average power delivered by the child?
17.25 W
A fisherman casts his bait toward the river at an angle of 25° above the horizontal. As the line unravels, he notices that the bait and hook reach a maximum height of 2.9 m. What was the initial velocity he launched the bait with? Assume that the line exerts no appreciable drag force on the bait and hook and that air resistance is negligible.
17.8 m/s
A 600-kg car makes a 90° turn. Its speed before the turn is 21.0 m/s and after the turn it is 24.0 m/s. What is the magnitude of the change in the car's momentum during the turn?
19.1 x 10^3 kg-m/s
Calculate the pressure exerted on the ground due to the weight of 79 kg person standing on one foot. if the bottom of the person's foot is 13 cm wide and 28 cm long.
2.1269 x 10^4 Pa
a 3kg mass and a 5kg 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?
2.45m/s2
what is the magnitude of the gravitational force that two small 7.0kg balls exert on each other when they are 35cm apart
2.67x10^-8
A girl throws a rock horizontally, with a velocity of 10 m/s, from a bridge. It falls 20 m to the water below. How far does the rock travel horizontally before striking the water, assuming negligible air resistance?
20.20 m
The temperature changes from 35°F during the night to 75°F during the day. What is the temperature change on the Celsius scale?
22 C
A lab assistant drops a 400.0-g piece of metal at 100.0°C into a 100.0-g aluminum cup containing 500.0 g of water at 15 C. In a few minutes, she measures the final temperature of the system to be 40.0°C. What is the specific heat of the 400.0-g piece of metal, assuming that no significant heat is exchanged with the surroundings? The specific heat of this aluminum is 900.0 J/kg ∙ K and that of water is 4186 J/kg ∙ K.
2273 .95 J/kg C
Three boxes rest side-by-side on a smooth, horizontal floor. Their masses are 5.0 kg, 3.0 kg, and 2.0 kg, with the 3.0-kg mass in the center. A force of 50 N pushes on the 5.0-kg box, which pushes against the other two boxes. What magnitude force does the 5.0-kg box exert on the 3.0- kg box?
25N
a 6kg box is held at rest by two ropes that form 30 degree angles with the vertical. an external force F acts vertically downward on the box. the force exerted by each of the rope is denoted by T. A force diagram, showing the four forces that act on box in equilibrium, is shown in the figure . the magnitude of force F is 410N. what is the magnitude of force T?
271N
Some properties of a certain glass are listed here: Density 2300 kg/m3 Specific heat capacity 840 J/kg ∙ C° Coefficient of thermal expansion 8.5 × 10-6 (C°)-1 Thermal conductivity 0.80 W/m ∙ C° A glass window pane is 2.7 m high, 2.4 m wide, and 9.0 mm thick. The temperature at the inner surface of the glass is 19 C and at the outer surface 4°C. How much heat is lost each hour through the window?
3.11 x 10^7 J
A 5.00-g lead BB moving at 44.0 m/s penetrates a wood block and comes to rest inside the block. If half of its kinetic energy is absorbed by the BB, what is the change in the temperature of the BB? The specific heat of lead is 128 J/kg ∙ K.
3.78 degrees C
Vector A has a magnitude of 4.0 m and points 30° south of east. Vector B has a magnitude of 2.0 m and points 30° north of west. The resultant vector A + B is given by
30 degrees East of South
A velocity vector has components 36 m/s westward and 22 m/s northward. What are the magnitude and direction of this vector?
31.42 degrees
A 4.0-kg cylinder of solid iron is supported by a string while submerged in water. What is the tension in the string? The density of iron is 7860 kg/m3 and that of water is 1000 kg/m3.
34.22 N
How much work must be done by frictional forces in slowing a 1000-kg car from 26.1 m/s to rest?
340,605 J
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?
4 s
A soccer ball is released from rest at the top of a grassy incline. After 6.4 seconds the ball has rolled 91 m with constant acceleration, and 1.0 s later it reaches the bottom of the incline. (a) What was the ball's acceleration? (b) How long was the incline?
4.44 m/s^2 121.56 m
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?
4.77 m/s
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?
4.997 m/s
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?
42 m
A mercury thermometer has a glass bulb of interior volume 0.100 cm3 at 10°C. The glass capillary tube above the bulb has an inner cross-sectional area of 0.012 mm2. The coefficient of volume expansion of mercury is 1.8 × 10-4 K-1. If the expansion of the glass is negligible, how much will the mercury rise in the capillary tube when the temperature rises from 5°C to 35°C if the bulb was full at 5°C?
45 mm
A traveler pulls on a suitcase strap at an angle 36° above the horizontal. If 555 J of work are done by the strap while moving the suitcase a horizontal distance of 15 m, what is the tension in the strap?
45.7 N
A heat engine having the maximum possible efficiency has an efficiency of 35.0% when operating between two heat reservoirs. If the temperature of the hot reservoir is 700 K, what is the temperature of the cold reservoir?
455 K
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?
49 m/s
The ocean thermal energy conversion project uses the surface water near tropical islands with a temperature of 20°C as the hot temperature reservoir, and the water at some depth, with a temperature of 5.0°C, as the cold temperature reservoir for a heat engine. What is the maximum possible efficiency of an engine running between those two temperatures?
5.1 %
An incompressible ideal fluid flows steadily through a pipe that has a change in diameter. The fluid speed at a location where the pipe diameter is 8.0 cm is 1.28 m/s. What is the fluid speed at a location where the diameter has narrowed to 4.0 cm?
5.12 m/sec
A light-year (ly) 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 1.00 ly? (1.00 mi = 1.609 km and one year is 365.25 days.)
5.88*10^12 miles
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?
575 J
A refrigerator has a coefficient of performance equal to 4.2. How much work must be done on the operating gas in the refrigerator in order to remove 250 J of heat from the interior compartment?
59.52 J or 60 J
this is the angular velocity of a wheel. how many revolutions does the wheel make in the first 4s?
6
The wavelength of the light from a certain laser is 0.66 microns, where 1 micron = 1.0 × 10-6 m. What is this wavelength in nanometers? (1 nm = 10-9m)
6.6 x 10^2 nm
an astronaut weighs 99N on the moon where the acceleration due to gravity is 1.62m/s^2. how much does she weigh on earth?
600N
Alicia intends to swim to a point straight across a 100 m wide river with a current that flows at 1.2 m/s. She can swim 2.5 m/s in still water. At what angle, measured from the upstream direction, must she swim upstream to achieve her goal?
61.3
a 1200kg car is pulling a 500kg trailer along level ground. friction of the road on the trailer is negligable. the car accelerates with an acceleration of 1.3m/s2. what is the force exerted by the car on the trailer?
650N
By what length will a slab of concrete that is originally 18 m long contract when the temperature drops from 24°C to -16°C? The coefficient of linear thermal expansion for this concrete is 1.0 × 10-5 K-1.
7.2 mm
It is necessary to determine the specific heat of an unknown object. The mass of the object is 201.0 g, It is determined experimentally that it takes 150 J to raise the temperature 100 oC. What is the specific heat of the object?
7.46 J/kg-K
A stone is thrown horizontally with an initial speed of 10 m/s from the edge of a cliff. A stopwatch measures the stone's trajectory time from the top of the cliff to the bottom to be 4.3 s. What is the height of the cliff if air resistance is negligibly small?
91 m
Suppose that an object travels from one point in space to another. Make a comparison between the magnitude of the displacement and the distance traveled by this object.
Displacement is either less than or equal to distance traveled
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 truck and car respectively, it is correct to say that
Kt = 16 Kc
A girl attaches a rock to a string, which she then swings counter-clockwise in a horizontal circle. The string breaks at point P in the figure, which shows a bird's-eye view (as seen from above). Which path (A-E) will the rock follow?
Path B
three boxes are pulled along a horizontal frictionless floor by a constant horizontal pull P. the boxes are connected by very light horizontal tensions T1 and T2 as shown in the figure. which of the following statements about the tensions is correct?
T1>T2
Which of the following statements are true about an object in two-dimensional projectile motion with no air resistance?
The horizontal acceleration is always zero and the vertical accelereation is always a non-zero constant downward
A small car meshes with a large truck in a head-on collision. Which of the following statements concerning the magnitude of the momentum change during the collision is correct? (There could be more than one correct choice.)
The small car and the truck experience the same magnitude and momentum change
A crane lowers a girder into place at constant speed. Consider the work WG done by gravity and the work WT done by the tension in the cable. Which is true
Wt is negative
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. 100 s b. 62.5 m/s
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
Consider two vectors A and B shown in the figure. The difference A - B is best illustrated by
arrow pointing right diagonally (d)
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
as small as 2m and as large as 12 m
A 5-kg ball collides inelastically head-on with a 10-kg ball, which is initially stationary. Which of the following statements is true? (There could be more than one correct choice.)
both balls lose their momentum since the collision is inelastic; the magnitude of the change of velocity is equal with both balls.
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 travel the same distance
As shown in the figure, a bimetallic strip, consisting of metal G on the top and metal H on the bottom, is rigidly attached to a wall at the left. The coefficient of linear thermal expansion for metal G is greater than that of metal H. If the strip is uniformly heated, it will
curve downward
in the figure what does the spring scale read. the pulleys are ideal and the strings and scale are also massless
exactly 1N
two small objects with masses m and M are originally a distance r apart and the magnitude of the gravitational force on each one is F. the masses are changed to 2m and 2M and the distance is changed to 4r. what is the magnitude of the new gravitational force?
f/4
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
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
You are making a circular turn in your car on a horizontal road when you hit a big patch of ice, causing the force of friction between the tires and the road to become zero. While the car is on the ice, it
moves along a straight line path in its original direction
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 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 absolute temperature of an ideal gas is directly proportional to which of the following quantities?
the average kinetic energy of its molecules
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 Δp, which of the following statements is correct?
the pressure everywhere in the oil will increase by (delta)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 Young's modulus
Two objects have masses m and 5m, respectively. They both are placed side by side on a frictionless inclined ramp and allowed to slide down from rest without any air resistance. Which one of the following statements about these objects is correct?
the two objects reach the bottom of the incline at same time
