physics
The location of the center of mass of a person:
can change if the person moves
For which of the following objects would the center of mass not lie within the object itself?
Doughnut
The weight of an object at the surface of Earth is 90 N. What is its weight at a distance 2R from the surface of Earth?
10 N
A 3-kg ball is rolling at a speed of 6 m/s. What is the magnitude of the momentum of the ball?
18 kg.m/s
What is the speed of a 0.145 kg object moving with a momentum of 5.80 Ns?
40.0 m/s
A satellite is orbiting the earth at an altitude where the acceleration due to gravity is 8.70 m/s2. What is its speed?
7.68x103 m/s
Which is a vector? I. Linear Momentum II. Impulse
both I and II
The mechanical energy of a system of objects is conserved:
not none of the above
An object of 2 kg mass, acted upon by a net force of 20 N, will experience what acceleration?
10 m/s2
A 5.0-kg brick is moving horizontally at 6.0 m/s. In order to change its speed to 10.0 m/s, the net work done on the brick must be:
160 J
If a car moving at 15 m/s skids to a stop after 20 m, how far will it skid if it is moving at 45 m/s? Assume that the braking force is constant.
180 m
A wheel rolling on a horizontal surface with an angular speed of 2.5 rad/s gets on a ramp and rolls down the ramp with a constant angular acceleration of 2.0 rad/s2. If it takes 11.5 s to reach the bottom of the ramp, what is the final angular speed of the wheel at the bottom?
25.5 rad/s
A 1500 kg car travels at a speed of 20 m/s. What is its kinetic energy?
3.0 x 105 J
Two point masses are placed 10.0 cm apart and attract each other with a force of 10.0 N. Find the force of gravitational attraction between the masses when they are placed 5.0 cm apart.
40.0 N
A car with a mass of 2000 kg is traveling at 10 m/s. What is the braking force needed to bring the car to complete stop in 5 seconds?
4000N
A physics student holds a 2.40-kg block against a wall by pressing on it perpendicularly to the wall. Find the minimum force she must exert if the coefficient of static friction is 0.32.
73.5
A 500 N weight is hung at the middle of a rope attached to two buildings at the same level. If the tension exceeds 1800 N the rope will break. What is the minimum angle the rope can make with the horizontal?
8o
What is the gravitational potential energy of a 1-kg block at rest on a table 1 m above the floor?
9.8 J
A 1300 kg sports car can accelerate from 0 to 27 m/s in 5.2 seconds. How much power from the engine is directly going into accelerating the car?
91,100 W
If the work done on a particle is zero, then:
all of the above are possible
A 3 kg object and a 4 kg object have the same linear momentum. Which object has larger kinetic energy?
the 3 kg object
Two bodies, masses m1 and m2, are at distance r from each other and attract each other with force F. Find the gravitational force if the distance is doubled.
F/4
A stone is thrown horizontally from the top of a tower at the same instant that another stone is dropped vertically. Which object is traveling faster when it hits the ground?
The first stone
A 2.0-kg object is acted on by a force F. The object is moving with acceleration of 10 m/s2. Find F.
20 N
Which of the following is NOT a vector?
Speed
Ruth is moving a heavy box a distance of 14.0 m across the floor of her bedroom. If she does 9000 J of work in 3.00 s, her power is _____.
3000 W
A 1.5 kg ball falls onto a floor. Just before it strikes the floor, its velocity is 12 m/s. The ball bounces up with a velocity of 10 m/s. Find the impulse on the ball.
33 N-s
A crate of a weight of 100 N is held in place on a smooth ramp by a rope parallel to the slope attached to a stake at the top of the ramp. What is the tension in the rope if the angle of inclination of the ramp is 20o
34 N
If the magnitude of the velocity of an object moving in a circular path doubles, the centripetal acceleration is multiplied by:
4
If a collision of two particles is not head-on, then which of the following is always true of the collision?
Momentum is conserved.
The amount of work required to stop a truck is equal to the:
kinetic energy of the truck
A 3 kg object and a 4 kg object have the same kinetic energy. Which object has larger momentum?
the 4 kg
A 5 kg projectile is fired at an angle of 25o above the horizontal. Its initial velocity is 200 m/s and just before it hits the ground its velocity is 150 m/s. What is the change in the mechanical energy of the projectile?
+44,000 J
A 6.00 kg block slides down a 3.40 m long inclined plane. The speed of the block at the bottom is 5.40 m/s. If the height of the plane is 2.00 m, what is the work done by friction?
-30.1 J
Two identical bodies are sliding toward each other on a frictionless surface. One moves at 1 m/s and the other at 2 m/s. They collide and stick. The speed of the combined mass is:
1/2 m/s.
A brick falls to the ground. If the time for the collision of the brick and the ground is increased by a factor of 4, the force of the collision with the ground will change by a factor of:
1/4
A 1-kg block starts sliding up a frictionless 30o inclined plane with an initial velocity of 4.00 m/s. How far does the block go up the ramp before stopping?
2.16 m
A grinding wheel has a radius of 0.30 m at rest and accelerates with a constant angular acceleration of 0.50 rad/s2. What is its tangential acceleration?
0.15 m/s2
The weight of a 0.6 kg object at the surface of Planet V is 20 N. The radius of the planet is 4 X 106 m. Find the gravitational acceleration at a distance of 2.0 X 106 m from the surface of this planet.
14.8 m/s2
An object that is acted upon by a net force of 20 N is moving with an acceleration of 10 m/s2. What is the mass of the object?
2 kg
A 20,000 kg car moving with a speed of 4.00 m/s collides with a 50,000 kg car moving with a speed of 1.80 m/s in the same direction. Find the speed of the combined cars after the collision which is perfectly inelastic.
2.43 m/s
A 0.30 kg ball is dropped onto a concrete driveway. The ball's velocity before impact is 4.5 m/s and after impact is 4.2 m/s. What is the change in the ball's momentum?
2.6 kg-m/s
A bullet is fired at an angle θ above the horizontal with an initial velocity of 800 m/s from the top of an 80 m high tower. What value of θ will give the maximum horizontal range?
45 degrees
Mass is a measure of an object's resistance to:
not speeding up
A force of 30.0 N is required to stretch a spring by 0.20 m. What work is done in stretching a spring from 0 to 0.40 m?
12.0 J
A 40 N box is pulled up an inclined plane at a constant velocity. If the plane is inclined at an angle of 37o to the horizontal and the box travels 5 m, what is the work done by the force of gravity?
120 J
A horizontal force, F, acts on a crate weighing 8 N, which moves on a horizontal floor at constant speed. The coefficient of friction between the crate and the surface is 0.25. The work done by F when the crate has moved 12 m is:
24 J
A 2,000-kg elevator is being accelerated upward at a rate of 3.0 m/s2. What is the tension in the cable?
25,600 N
A 2000-kg ore car rolls 50 meters down a smooth 10o incline. There is a horizontal spring at the end of the incline designed to stop the car in case of break failure. What is the spring constant of the spring if it would compress by 1 m to stop the ore car?
340 kN/m
A 3 kg object traveling at 4 m/s is pushed by a net force of 5 N. The speed increases to 6 m/s. Find the distance the object travels.
6 m
In an inelastic collision:
momentum is conserved, but not kinetic energy.
A force of 250 N pushes a 50-kg box along a horizontal surface. The force is directed 30o below the horizontal. What is the acceleration of the box if the coefficient of kinetic friction between the box and the surface is 0.30?
0.637 m/s2
A 43-kg child sits in a massless swing. With what horizontal force must the seat be pulled so that the ropes form an angle of 35o with respect to the vertical?
300 N
The center of mass of a body can be outside of the body:
True
The mass of Planet W is 1/100 that of Earth and its radius is 1/4 that of Earth. If the weight of an object is 600 N on Earth, what would it weigh on Planet W?
96 N
A 1500-kg car moving at 15 m/s strikes another car at rest. The two cars continue to move together at 10 m/s. What was the mass of the second car?
750 kg
A ball with momentum p strikes a wall and bounces off at the same speed. The change in the ball's momentum is:
2p
Two blocks are released from the top of a tower. One falls straight down while the other slides down a frictionless ramp. Which one is moving faster when it reaches the bottom
They both will have the same speed
A roller coaster loop has a radius of 12 m. What is the minimum speed the coaster must have at the top?
11 m/s
A car starts from rest and in ten seconds is moving at 40 m/s. What is the car's acceleration?
4.0 m/s2
An airplane is accelerating at a constant rate of 15 m/s2. How much time does it take for the airplane to increase its speed from 100 m/s to 160 m/s?
4.0 s
While accelerating at a constant rate from 12.0 m/s to 18.0 m/s, a car moves over a distance of 60.0 m. How much time does it take?
4.00
A missile is launched upward with a speed that is half the escape speed. What height (in radii of Earth) will it reach?
R/3
You jump off a truck and accelerate toward the surface of the Earth. Does the Earth accelerate toward you?
Yes, but the acceleration of the Earth is very small
A bullet with a mass of 3.0 gram, moving at speed of 300 m/s, hits and embeds itself in the trunk of a tree. The tree exerts an average force of 250 N on the bullet. What is the distance the bullet travels inside the trunk?
0.54 m
A swimmer dives horizontally off a 500 kg raft. If the diver's mass is 75 kg and his speed while leaving the raft is 4 m/s, what is the raft speed?
0.6 m/s.
What is the acceleration due to gravity on the surface of the planet Pluto if its mass is 1.20x1022 kg and radius is 1.14x106 m?
0.62 m/s2
The value of g at an altitude above Earth equal to one Earth diameter is:
1.1 m/s2
Mike stands on a scale in an elevator. If the elevator is accelerating upwards with 4.9 m/s2, the scale reading is ____ times Mike's weight.
1.5
For safety reasons, the speed of a child at the bottom of a playground slide cannot exceed 6.0 m/s. What is the maximum height of the slide?
1.8 m
If it takes 40 J to push a large box 4 m across a floor, what is the magnitude of the force on the box? The push is in the same direction as the velocity of the box.
10 N
A 2 kg ball moving at 3 m/s hits a wall and bounces off. Immediately after the collision, it moves at 3 m/s in the opposite direction. What is the change in the object's momentum?
12 kg m/s -12 kg m/s
Mike jumps 1 m down onto a walkway. His downward motion stops in 0.02 seconds. If he forgets to bend his knees, what force is transmitted to his leg bones? Mike's mass is 70-kg.
15,490 N
A car rounds a 75-m radius curve at a constant speed of 18 m/s. A ball is suspended by a string from the ceiling of the car. What is the angle between the string and the vertical?
24°
A flywheel with a radius of 0.15 m starts from rest and reaches an angular speed of 12.0. What is the wheel's angular acceleration if it reaches this speed in 4.0 s?
3.0 rad/s2
The distance between the center of masses of two objects is 4.60 m. The masses of the objects are 24.4 kg and 45.8 kg. What is the distance of the center of mass of the two objects from the center of mass of the 24.4 kg object?
3.00
A 1.5 kg object falls from a height of 2.0 m onto a spring scale with a spring constant of 1.5x105 N/m. What is the reading on the scale at its greatest compression?
3.0x103 N
An object moves in a circle. If the mass is tripled, the speed halved, and the radius unchanged then the centripetal force must change by a factor of:
3/4
An arrow is shot with an initial velocity of 60.0 m/s at an angle of 30.0° above the horizontal. What is the maximum height it will reach?
46 m
Two objects with masses 500 kg and 2000 kg are moving at the same speed. What is the ratio of the kinetic energy of the second object to the kinetic energy of the first object?
4:1
A pendulum is pulled to a height of 1.28 m above the lowest position and released. What is its speed at the level of the lowest position?
5 m/s
A car starts from rest and reaches a speed of 50 m/s in 10 s. What is its average acceleration?
5 m/s2
Two trucks with the same masses are moving toward each other along a straight line with speeds of 50 mi/h and 60 mi/h. What is the speed of combined trucks after completely inelastic collision?
5 mi/h
Bill pushes a 250 N weight wheelbarrow up a 6.0 m long ramp making 20o angle with the horizontal. Find the change in the gravitational potential energy of the wheelbarrow.
513 J
Two forces act on a 5-kg object. One force is 40 N and directed east. The other force is directed west. The acceleration of the object is 3 m/s West. What is the magnitude and direction of the second force?
55 N West
John is running up stairs rising vertically 4.0 m in 4.2 s. What is the power supplied by his muscles if his mass is 60.0 kg?
560 W
John pulls a sled on a frictionless surface with a force of 60 N at an angle of 37o above the horizontal. If he pulls it a distance of 12 m, the work he does is:
575 J
A 3.00 kg ball makes a perfectly inelastic collision with a second ball that is initially not moving. The combined balls move with a speed equal to one third the original speed of the first ball? What is the mass of the second ball?
6.00 kg
A 40.0 N cart slides from rest down a rough 6.0 m long ramp inclined at 30.00 with the horizontal. Find the velocity of the cart at the bottom of the ramp if the force of friction between the cart and ramp is 6.0 N.
6.4 m/s
A pulley-cable system on a construction site lifts a 20,000 N concrete block to a height of 40 m. If this takes 2 min., what is the power of the pulley-cable system
6.7 kW
A soccer player kicks a soccer ball initially at rest setting it in motion at a velocity of 30 m/s. If the ball has a mass of 0.5 kg and the time of contact is 0.025 s, what is the force exerted on the player's foot?
600 N
A 2000 kg roller coaster is at the top of a loop with a radius of 24 m. If its speed is 18 m/s at this point, what force does it exert on the track? (g = 9.8 m/s2)
7.40 x 103 N
How far from the center of the Earth is the point where the net force of the gravitational attraction of the Earth and the moon is zero? The mass of the moon is 1/81 that of the Earth.
9/10 the way to the moon
A cart of known mass moves with known speed along a level, frictionless track, as shown in the figure above. The cart hits a force sensor and rebounds. The force sensor measures the force exerted on the cart as a function of time and as a function of the position of the cart. The results will be graphed on the axis shown. Which of the two graphs can be used to determine the carts speed after it rebounds?
Either graph 1 or graph 2 can be used.
Select the best answer to the following question: Can potential energy of a system be negative?
Yes, since the choice of the zero of potential energy is arbitrary.
A box rests on a level table. Let W be the weight of the box, and N is the normal of the table on the box. In magnitude, W is opposite and ___ N, and the two forces ___ action-reaction pair.
equals, are not
A bumper protects a car during a collision because it:
increases the time of impact
The property of matter referred to in the question above is called:
inertia
If a shell fired from a canon explodes in midair:
its total kinetic energy increases.
The periods of a satellite orbiting a planet does not depend on the:
mass of the satellite
A horizontal force drags a box across a floor. If another force of the same magnitude but an angle above the horizontal is applied, the force of kinetic friction:
not become greater
Various radial points on a rotating Ferris wheel have ______ linear velocities and _______ angular velocities.
not equal, different
The work done by the centripetal force acting on an object moving at a constant linear speed is:
not greater than zero since it takes energy to turn an object
An object in motion need not have:
not kinetic energy
A pilot drops a bomb from a plane flying horizontally. Where will the plane be located when the bomb hits the ground?
over the bomb
Which of the following is associated with an object due to its position?
potential energy
The rate at which work is done is equivalent to:
power
If two objects have the same momentum, then:
the object with the greater mass will have the smaller velocity
An elephant is hit by a ping pong ball. The magnitude of the change in momentum is
the same for both
A truck moving at 13.3 m/s hits a concrete wall. As a result of the collision, a 6-kg wrench moves forwards and strikes the wall of the tool compartment. If the wrench stops after being in contact with the wall for 0.07 s, what is the average force exerted on the wrench by the wall?
1140 N
A person is running on a track. Which of the following forces propels the runner forward?
The force of friction exerted by the ground on the person
If a net force is acting on an object, then _______________.
The object is being accelerated
Bill weighs 160 lb. He is standing on a scale inside an elevator. What is the reading on the scale if the elevator is accelerating downward?
less than 160 lb
A 0.240 kg glider moving with a velocity of 0.600 m/s collides head-on with a 0.260 kg glider moving along the same line in the opposite direction with a velocity of 0.200 m/s. The collision is perfectly inelastic. The final velocity of the combined gliders is _____ m/s.
0.184
A turntable reaches an angular speed of 45 rev./min. in 4.1 s after being turned on. What is its angular acceleration?
1.15 rad/s2
Two masses are precisely 1 m apart from each other. The gravitational force each exerts on the other is exactly 1 N. If the masses are identical, what is each mass?
1.22x105 kg
A ball hits a wall head on and sticks to it. If instead the ball bounces off the wall with one-half of the original velocity and the collision lasts the same time, the average force on the ball would be _____ times greater.
1.5
A ballistic pendulum is a device used to measure the speed of a bullet. A bullet is fired at a block of wood hanging from two strings. The bullet embeds itself in the block and causes the combined block plus bullet system to swing up.If the bullet is fired at 530 m/s and its mass is 6.5 g, what is the speed of the block with embedded bullet after collision? The mass of the block is 2.2 kg.
1.6 m/s
Use Kepler's Law to find the time (in Earth's years) for Mars to orbit the sun if the radius of Mars' orbit is 1.5 times the radius of Earth's orbit.
1.8
The force constant of a spring in a lab spring scale is 100 N/m. The spring is compressed by 0.2 m. How much energy has the spring stored?
2.0 J
A 15,000 kg railroad freight car is coasting at a speed of 2 m/s. It collides and couples with another car with a mass of 50,000 kg, which was initially not moving. What percentage of the initial kinetic energy of the system is preserved after collision?
23%
A driver, traveling at 22.0 m/s, slows down her car and stops. What work is done by the friction force against the wheels if the mass of the car is 1500 kg?
3.6 x 105 joules
A 2.0 x 103 kg roller coaster travels around a vertical 24-m radius loop. If the coaster has a tangential speed of 18 m/s at the lowest point of the loop, what is the normal force that is exerted on the coaster by the track at this point?
4.7 x 104 N
The maximum speed a car can round an 80-m radius horizontal curve without slipping is 20 m/s. How fast can this car round a 320-m radius curve on the same road?
40 m/s
An 800-N box is pushed up an inclined plane. The plane is 4.0 m long and 2.0 m high. If it requires 3200 J of work to get the box to the top of the plane, what was the magnitude of the average friction force on the box?
400 N
A car starts from rest and moves with constant acceleration of 2 m/s2 for 10 s. Then it travels with constant speed for another 10 s before it slows to a stop with constant acceleration of -2 m/s2. How far does it travel?
400 m
What upward velocity must a basketball player have to jump 1.6 m off the floor?
5.6 m/s
A helicopter is flying at 40 m/s at an altitude of 100 m. If a ball is released from the helicopter, with what velocity will it hit the ground?
60 m/s
A weight of 5000 N is suspended by two cables. The object is at rest. The first cable is horizontal and the second makes an angle of 143o with the first cable. Find the tension of the first cable.
6640 N
The linear momentum of a bullet-gun system is zero before the gun fires. Afterwards: I. the kinetic energy is zero II. the momentum is zero
II
A particle is moved from point A to point B against a conservative force. Which statement is true about the work done?
not cannot be recovered by moving it from B to A
Box A of mass m sits on the floor of an elevator, with box B of mass 2m on top of it, as shown in the figure above. The elevator is moving upward and slowing down. FA is the magnitude of the force exerted on box A by box B, FB is the magnitude of the force exerted on box B by box A, and Fg is the magnitude of the gravitational force exerted on box B. which of the following ranks the forces in order of increasing magnitude?
(FB = FA) < Fg
A rock is thrown upward from the edge of a cliff that is 20 m high. The object rises 15 m and then falls to the ground. If the positive direction of the x is up, what is the rock's displacement?
-20 m
8.0 N
0.70
A car comes to a stop over a distance of 30.0 m after the driver applies the breaks. If the car decelerates at a constant rate of 3.50 m/s2, what was the car's original speed?
14.5 m/s
A rifle bullet is fired from the top of a cliff at an angle of 30o below the horizontal. The initial velocity of the bullet is 800 m/s. If the cliff is 80 m high, how far does it travel horizontally?
140 m
What distance does a train travel while slowing from 28 m/s to zero in 12 s?
168 m
A ball is launched at an angle of 40° above the horizontal at a speed of 16.0 m/s from the top of a 12.4 m tall building. What is the maximum height of the ball above the ground?
17.8
Two forces act on an object. A 10 N force is directed North and a 5 N force South. The object moves at constant acceleration of 2 m/s2. What is the mass of the object?
2.5 kg
A stone is thrown with an initial speed of 12 m/s at an angle of 30o above the horizontal from the top edge of a cliff. If it takes the stone 5.6 s to reach the bottom, how far does the stone travel horizontally? Neglect air resistance.
58 m
A stone is thrown horizontally with an initial speed of 10 m/s from the edge of a cliff. It hits the ground in 4.3 s. What is the height of the cliff?
91 m
A stone is thrown straight up. While the stone is rising:
None of the above.
A car moving south slows to a stop. What is the direction of the acceleration of the car?
North
A stone is thrown straight up. What is the magnitude of its acceleration at the top of its trajectory?
about 10 m/s2
In Newtonian mechanics, ____ is the cause and _____ the effect.
force, acceleration
If you push a car with a force F, the force that the car exerts on you:
is F in all cases
A ball is thrown straight up. At the highest point of its trajectory
its velocity is zero and its acceleration is not zero.
If a car is moving with constant velocity, then we can say that:
the sum of the external forces acting on the car is zero
All objects tend to maintain their state of motion because they have:
mass
A car that is moving at a speed of 15 m/s is coming to a complete stop in 5.2 seconds. What is the acceleration of the car?
-2.9 m/s2
An object, accelerating from rest at a constant rate, travels over 28 m in 11 s. What is its final velocity?
5.1 m/s
A projectile is launched with an initial velocity of 60.0 m/s at an angle of 37.0o above the horizontal. What is the maximum height reached by the projectile?
67 m
A projectile is launched from the ground at an angle of 15° above the horizontal. If the projectile is launched at the same velocity at an angle of _____, it will travel the same horizontal distance.
75°
A basketball player throws a ball at an angle of 30° above the horizontal. If the ball in the problem above has initial velocity of 29.4 m/s, how far does it travel?
76.4 m
Blocks A and B are moving toward each other along the x axis. A has a mass of 2 kg and a velocity of 50 m/s, while B has a mass of 4 kg and a velocity of -25 m/s. They collide head-on in an elastic collision. After the collision the velocities of A and B, respectively, are:
-50 and 25 m/s
A 1,500 kg car moving with a speed of 4.00 m/s collides with a 50,000 kg truck moving with a speed of 1.80 m/s in the same direction. If the collision is perfectly inelastic, the change in kinetic energy of the car is _____ .
-9,390
A coin is fixed in place 11 cm from the axis of a rotating turntable. The angular speed of the turntable is increased and when it reaches 36 rev/min the coin slides off. What is the coefficient of static friction between the coin and the turntable?
0.16
A 60 g golf ball is dropped from a level of 2 m high. It rebounds to 1.5 m. How much energy is lost?
0.29 J
An object with mass m is suspended at rest from a spring with a spring constant of 200 N/m. The length of the spring is 5.0 cm longer than its unstretched length L, as shown above. A person then exerts a force on the object and stretches the spring an additional 5.0 cm. What is the total energy stored in the spring at the new stretch length?
1.0 J
A 200-gram baseball traveling at 48 m/s is hit by a bat and rebounds in the opposite direction at 52 m/s. Find the average force of the bat on the ball if the time of contact is 2.0x10-3 s.
1.0 x 104 N
How far will the block in the problem above travel if the surface is rough and the coefficient of kinetic friction between the block and the ramp is 0.2.
1.75 m
A 50 kg athlete running at a speed v grabs a light rope that hangs from a 10 m high platform and swings to a maximum of 1.8 m above the ground. Later, a 100 kg athlete, running at the same speed, grabs a similar rope hanging from a 5 m high platform. What is the maximum height to which the 100 kg athlete swings?
1.8 m
A rubber ball is dropped on the floor. The rebound speed is one-half the speed it had just before hitting the floor. It will rise to ________ of the original height from which it was dropped.
1/4
The distance between a spaceship and the center of the Earth increases from 1.5 Earth radii to 3.0 Earth radii. By what factor does the force of gravity acting on the spaceship change?
1/4
A roller coaster travels around a vertical 8-m radius loop. Determine the speed at the top of the loop if the normal force exerted by the seats on the passengers is equal to ¼ of their weight.
10 m/s
An 80,000 kg plane is flying at 900 km/h at a height of 10 kilometers. What is its total mechanical energy?
10,340 MJ
A pole vaulter clears 6.00 m. What is his velocity just before landing?
10.8 m/s
A boy on a roof throws one ball downward and an identical ball upward. The ball thrown downward hits the ground with 100 J of kinetic energy. If both balls are thrown at the same speed and there is no air friction, what is the kinetic energy of the second just before it hits the ground?
100 J
Sarah and her bicycle have a total mass of 40 kg. Her speed at the top of a 10 m high and 100m long hill is 5 m/s. If the force of friction on her way down is 20 N, at what speed will she be going when she reaches the bottom?
11 m/s
A ballistic pendulum is a device used to measure the speed of a bullet. A bullet is fired at a block of wood hanging from two strings. The bullet embeds itself in the block and causes the combined block plus bullet system to swing up. The bullet is fired at 530 m/s, its mass is 6.5 g and the mass of the block is 2.2 kg. How high will the pendulum & bullet rise? (g = 9.8 m/s2)
12 cm
A 40.0 N crate is pulled up a 5.0 m inclined plane. The angle of inclination of the plane to horizontal is 37o. If there is a constant force of friction of 10.0 N between the crate and the surface, what is the net gain in potential energy by the crate?
120 J
A 20.0-N weight starts from rest and slides down a 150 m long inclined plane which makes an angle of 30o with the horizontal. At the bottom of the plane, the speed of the weight is 15.0 m/s. What work is done by friction?
1270 J
A force F is exerted on a 5 kg block to move it across a rough surface, as shown above. The magnitude of the force is initially 5 N, and the block moves at a constant velocity. While the block is moving, the force is instantaneously increased to 12 N. How much kinetic energy does the block now gain as it moves a distance of 2 m?
14 J
At what angle should the roadway on a curve with a 50m radius be banked to allow cars to negotiate the curve at 12 m/s even if the roadway is frictionless?
16
A 0.30 kg rock is rotating in a vertical plane on a 0.25 m long string. At the top of the path, the velocity is 4.0 m/s. Find the tension in the string at that point. Correct answer:
16.3 N
What is the maximum speed that a 2200 kg car can go around a level circular track with a radius of 30.0 m without slipping if the coefficient of static friction between the tires and the road is 0.900?
16.3 m/s
A 5.0-kg bowling ball is moving at 6.0 m/s. In order to change its speed to 10.0 m/s, the net work done on the bowling ball must be:
160 J
At what angle relative to the horizontal should a 52 m radius curve be banked if the road is covered with ice (no friction) to prevent the car from slipping when traveling at 12 m/s? (g = 9.8 m/s2)
16o
A 0.40 kg object attached to the end of a 0.50 m string rotates in a vertical circle. If the angular speed of the object at the bottom of the circle is 8.0 rad/s, what is the tension in the string at this point?
17 N
A 500 kg roller coaster car crests a 20m high hill at a speed of 10 m/s. It then rolls down the other side, all the way to ground level, and climbs a second hill. What is the speed of the car when it is 10 m up the second hill?
17.2 m/s
A 0.50 kg projectile is fired with an initial speed of 10 m/s at an angle of 60o above the horizontal. What is the potential energy of the projectile at the highest point of its path?
18.75 J
What is the work required to stretch a spring with a spring constant k of 2500 N/m by 4.00 cm?
2 J
Planet X has twice the mass and three times Earth's radius. The magnitude of the gravitational field near planet X's surface is most nearly:
2 N/kg
A pendulum, 2.0 m in length, is released with a push when the string is at an angle of 25o from the vertical. If the initial speed of the pendulum is 1.2 m/s, what is its speed at the bottom of the swing?
2.3 m/s
A 1200-kg boat is moving at 20 m/s. Its momentum is:
2.4 x 104 N-s
A billiard ball moving at 5 m/s strikes another ball which is initially at rest. After the collision, the first ball moves at a velocity of 4.35 m/s at an angle of 30o below its original motion. Find the velocity and angle of the second ball after the collision. Assume that the collision is perfectly elastic. Correct answer:
2.50 m/s @ 60o
A loaded sled weighs 5000 N. It is pulled on level snow by a horizontal force. The coefficient of kinetic friction between sled and snow is 0.05. How much work is done by the force if the sled traveled 1000 m at constant speed?
2.5x105 J
A 150 N sled is being pulled up a 28° rough ramp at constant speed by a force of 100 N parallel to the ramp. With what acceleration will the crate slide down, if it is released at some point on the ramp?
2.67 m/s2
An 80-N crate is pushed at constant speed for a distance of 5.0 m upward along a smooth inclined plane that makes an angle of 30o with the horizontal. If the force on the crate is parallel to the slope, what is the work done by the pushing force?
200 J
An object is thrown vertically upward with an initial kinetic energy of 4000 J from the level where its potential energy is 6000 J. When it is halfway to its highest point, its kinetic energy will be _____ J and its potential energy will be ______ J.
2000, 8000
A jet engine is moving an airplane forward at a speed of 900 km/hr. If the thrust of the engine is 105 N, what is the power developed by the engine?
25 MW
Sam is using a rope to pull a box weighing 300 N across a floor with constant velocity. The rope makes an angle of 30o above the horizontal. If the tension in the rope is 100 N, what is the normal force exerted by the floor on the box?
250 N
An 80-N crate is pushed a distance of 5.0 m upward along a smooth incline that makes an angle of 30o with the horizontal. The force pushing the crate is parallel to the slope. If the speed of the crate increases at a rate of 1.5 m/s2, find the work done by the force.
260 J
A pair of "fuzzy dice" hangs from a string attached to the rear view mirror of a race car moving with constant acceleration. Find the acceleration if the string makes a 70o angle with the vertical.
27 m/s2
A fighter jet of mass 9600 kg is moving at a speed of 72 m/s. If its total energy is 2.60x108 J, how high from the ground is it?
2760 m
A car with a mass of 1000 kg is moving on an un-banked ramp with a radius of 100 m. What is the maximum speed the car can move without skidding if the coefficients of static and kinetic friction are 0.80 and 0.60 respectively?
28 m/s
A crate is pulled 7.0 m across a smooth surface. The tension in the rope pulling the crate is 40 N. If the work on the crate is 247 J, what is the angle the rope makes with the horizontal?
28o
The radius of Planet Z is 3 times the radius of the Earth. It has the same density as the Earth. What is the gravitational acceleration at the surface of the planet?
29.4 m/s2
An object falls from a height of 10.0 m. If its mass is 3.00 kg, what is its kinetic energy just before the objects hits the ground?
294 J
The inclined plane in the figure above has two sections of equal length and different roughness. The dashed line shows where section 1 ends and section 2 begins. A block of mass M is placed at different locations on the incline. The coefficients of kinetic and static friction between the block and each section are shown in the table below. If the block is sliding up section 2, what is the magnitude of the force of friction that is exerted on the block by the incline?
2µk1 Mg cosθ
A ball is dropped from a roof of a building and strikes the ground in 3 seconds. If a second ball is thrown horizontally from the roof, it will hit the ground in:
3 s
A 6000N crate is pulled across an icy surface. The coefficient of kinetic friction is 0.05. The work done in pulling the crate 1000 m at constant velocity is:
3.0x105 J
A sports car accelerates at a constant rate from rest to a speed of 90 km/hr in 8 s. What is its acceleration?
3.1 m/s2
An object, which is initially at rest, is moving with a constant acceleration of 2.90 m/s2 over a distance of 15.2 m. How long does it take for the object to move over this distance?
3.23 s
In a device known as an Atwood machine, two masses m1 = 10 kg and m2 = 20kg are connected by rope over a frictionless pulley. What is the acceleration of each mass if the rope is massless?
3.33 m/s2
Two blocks with masses 2.00 kg and 4.00 kg are placed side-by-side on a frictionless horizontal surface. A horizontal force with a magnitude of 5.20 N is applied to the 2.00-kg block perpendicular to its surface. What is the magnitude of the force on the 4.00-kg block?
3.47
A 3-kg mass attached to a string which goes vertically to a pulley rests on the floor. A weight is attached to the other end and released. If the 3-kg mass rises 50 cm in 1.0 s, what is the mass of the weight?
3.67 kg
A 1.0-kg ball falls to the floor. When it is 0.70 m above the floor, its potential energy exactly equals its kinetic energy. How fast is it moving at this moment?
3.7 m/s
A 15.0 kg crate, initially at rest, slides down a 2.0 m long frictionless ramp inclined at an angle of 20o. What is the velocity of the crate at the bottom of the ramp? (g = 9.8 m/s2)
3.7 m/s
The mass of Mars is about 1/10 the mass of Earth. Its diameter is about 1/2 the diameter of Earth. What is the gravitational acceleration at the surface of Mars?
3.9 m/s2
A 0.2-kg stone attached to a string is swung in a circle with a radius 0.6 m on a horizontal frictionless surface. What is the tension in the string if the stone makes 150 revolutions per minute?
30 N
A 1000-kg sports car of mass accelerates from rest to 20 m/s in 6.6 s. What is the force exerted by the road on the car?
3000 N
A cannonball is fired from the ground at an initial speed of 40 m/s at an angle of θ above the horizontal. It takes 2.0 s for the cannonball to reach its maximum vertical height. What was the angle θ?
30o
An object is dropped from the edge of a cliff and is moving at 26.5 m/s just before it hits the ground. How high is the cliff?
35.8 m
A 0.145 kg rock is thrown with a speed of 32.0 m/s at an angle of 40o. What is its kinetic energy at the top of its trajectory?
43.6 J
A 1.50-kg mass is acted upon by a force of 16.0 N applied at an angle of 60o above the horizontal. What is the acceleration of the mass?
5.33 m/s2
A car is traveling at a constant speed of 22 m/s around a curve with a radius of 85 m. What is the car's acceleration?
5.7 m/s2
A 9.0 × 10 3 kg satellite orbits the earth at the distance of 2.56 × 10 7 m from Earth's surface. What is its period?
5.7 × 10 4 s
An 8000-N car is moving at 12 m/s along a horizontal road. The driver applies the breaks and the car skids to a stop. How much kinetic energy is lost?
5.9x104 J
A 5-kg fish moving at a speed of 1 m/s swallows 1-kg fish at rest. Its speed after this is:
5/6 m/s.
What is the smallest value of the force that must be applied to prevent the 3.0-kg block in the diagram below from sliding down the wall?
50 N
A 2.0-kg stone swings in a vertical circle on the end of a 1.0-m string. Find the tension of the string at the bottom point if the speed of the stone at this point is 4.0 m/s.
52
A truck increases its speed from 8 m/s to 28 m/s over a distance of 120 m? How long does this take? Assume that the acceleration is constant.
6.7 s
A roller coaster car starts out at rest at the top of the first hill and reaches a speed of 10 m/s at the bottom of the hill. What is its speed when it is half-way down? Assume that the track is frictionless.
7.1 m/s
Two forces, 300 N and 500 N, act on an 80-kg particle. 300 N north and 500 N east. Find the magnitude of the resultant acceleration if the forces make a 90o angle with each other.
7.29 m/s2
Suppose that 56 J of work was done to increase the kinetic energy of a 1.90-kg mass. If the object's initial velocity was zero, what is its speed now?
7.7 m/s
A 3400 kg plane flying at a constant speed of 170 m/s is to do a vertical loop. What is the radius of the loop if the pilot feels three times his normal weight when he is at the top of the loop?
737 m
A planet Y is moving in circular orbit around the Sun. If its distance from the Sun is four times the average distance of the Earth from the Sun, what is the Y's period in Earth years?
8
A 2.0-kg laptop sits on the horizontal surface of the seat of a car moving at 8.0 m/s. The driver starts slowing down to stop. Find the minimum stopping distance so the computer does not slip and fall onto the floor if the coefficient of static friction between the seat and the laptop is 0.40 and the coefficient of kinetic friction is 0.20.
8 m
A 5.0-kg object attached to the end of a 4.0-m rope is moving in a vertical circle. What is the object's linear velocity at the top of the circle if the tension in the rope at this point is 30 N?
8 m/s
A crate is pulled across a horizontal floor by a rope tied to the crate. The rope makes an angle of 37 degrees with the horizontal. Find the frictional force if the tension in the rope is 10N and the crate moves with constant velocity.
8.0 N
The radius of the orbit of a certain asteroid is four astronomical units. What is the period (in years) of this asteroid?
8.00 years
A ball thrown horizontally from the top of a building 24 m above the ground strikes the ground at the distance of 18 m from the base of the building. What was its initial velocity? (Use g = 10 m/s2.)
8.22 m/s
Jim climbs up a rope from an initial height of 1.30 m to a final height of 3.20 m. If Jim's mass is 45 kg, what is the change in his gravitational potential energy?
838 J
The weight of a 0.5 kg object on the surface of Planet X is 20 N. If the radius of the planet is 4 X 106 m, what is its mass?
9.6 X 1024 kg
A soccer ball is kicked with a velocity of 25 m/s at an angle of 45o above the horizontal. What is the vertical component of its acceleration as it travels along its path?
9.80 m/s2 downward
The driver of a 2000 kg car moving at 30 m/s presses on the break pedal. If the braking force is 10,000 N, how far does the car travel before stopping?
90 m
An object accelerates if it:
All of the above.
If a 60-ton Patton tank collides with a little Honda Civic, which vehicle will experience the greater impact force?
Both the same
The graph above shows velocity as a function of time t for a 0.50 kg object traveling along a straight line. The graph has three segments labeled 1, 2, and 3. A rope exerts a constant force of magnitude FT on the object along its direction of motion the whole time. During segment 2 only, a frictional force of magnitude Ff is also exerted on the object. Which of the following expressions correctly relates the magnitudes Ff and FT?
FT < Ff < 2FT
A 2 kg object traveling at 5 m/s on a frictionless horizontal surface collides head-on with and sticks to a 3 kg object initially at rest. Which of the following correctly identifies the change in total kinetic energy and the resulting speed of the objects after the collision?
KE Decreases v = 2 m/s
An apple falls from a tree. How do its KE and GPE change as it falls to the ground?
KE increases, and GPE decreases
Which of the following has the largest kinetic energy?
Mass 2M and speed 3V
The inclined plane in the figure above has two sections of equal length and different roughness. The dashed line shows where section 1 ends and section 2 begins. A block of mass M is placed at different locations on the incline. The coefficients of kinetic and static friction between the block and each section are shown in the table below. If the block is at rest on section 1 of the incline, what is the magnitude of the force of static friction exerted on the block by the incline?
Mg sinθ
You and your friend push against a wall. Your friend stops after 10 min, while you push for 5 min longer. Compare the work you and your friend do.
Neither you nor your friend does any work.
A tennis ball moving at a speed of 4 m/s, collides with a bowling ball at rest. The tennis ball bounces back in the direction opposite to the initial velocity, and the bowling ball moves very slowly too. Which object experiences the greater magnitude impulse during the collision?
Neither, both experienced the same magnitude impulse
If the instantaneous velocity of an object is zero, then its acceleration must be:
Not enough information.
Some students want to calculate the work done by friction as an object with unknown mass moves along a straight line on a rough horizontal surface. The students have a force probe, a meter stick, and a stopwatch. Which of the following will allow the students to take the measurements needed to calculate the work done by friction?
Pulling the block at an unknown constant speed with the force probe for a measured distance.
The magnitude of the gravitational field on the surface of a particular planet is 2g. the planet's mass is half the mass of Earth. What is the planet's radius in terms of the radius RE of earth?
RE /2
A kitten sits in a lightweight basket near the edge of a table. A person accidentally knocks the basket off the table. As the kitten and the basket fall, the kitten rolls, turns, kicks, and scratches in the basket with its claws. The basket lands on the floor with the kitten safely inside. If air resistance is negligible, what is the acceleration of the kitten-basket system while the kitten and basket are in midair?
The acceleration is directed downward with a magnitude equal to g because the system is a projectile.
An object's velocity v is a function of time t is given in the graph above. Which of the following statements is true about the motion of the object?
The objects initial and final positions are the same.
A croquet mallet balances when suspended from its center of mass, as shown in the figure below. If the mallet is cut in two at its center of mass, how do the masses of the two pieces compare?
The piece with the head of the mallet has the greater mass.
A person holds a book at rest a few feet above the table. The person then lowers the book at a slow constant speed and places it on the table. Which of the following accurately describes the change in the total mechanical energy of the Earth-book system?
The total mechanical energy decreases, because the person does negative work on the book by exerting a force on the book in the direction opposite to its displacement.
Which of the following is a correct statement of the law of conservation of momentum?
The total momentum of an isolated system of bodies remains constant.
A cannonball explodes into several fragments in mid-air. The total momentum of the fragments after this explosion:
is the same as the momentum of the cannonball immediately before the explosion
An object thrown vertically upward will ________ kinetic energy and ________ gravitational potential energy.
lose ... gain
A 1000 kg car traveling east at 20 m/s collides head-on with a 1500 kg car traveling west at 10 m/s. The cars stick together after the collision. What is their common velocity after the collision?
none of these
A 40 kg boy dives horizontally off a 600 kg raft. If the boy's speed at the moment he is leaving the raft is 4 m/s, what is the raft's speed?
none of these
A block slides down an inclined plane. Which force does zero work?
normal force
In a one-dimensional perfectly elastic collision, an object of mass m is traveling with speed v0 in the + x-direction when it strikes an object with mass 3m that is at rest. What are the objects velocities following the collision?
not vm = v0/2 +x-direction v3m = v0/2 +x-direction
A horizontal force of 5 N accelerates a 4-kg object from rest at 0.5 m/s2. What friction force acts on the object?
not +3 N
A spring is hung from the ceiling. A 2.0-kg mass suspended hung from the spring extends it by 6.0 cm. A downward external force applied to the mass extends the spring an additional 10 cm. What is the work done by the force?
not -3.6 J
A force of 50-N directed 30o above the horizontal is applied to a 10-kg block at rest on a rough horizontal surface. What is the coefficient of kinetic friction between the block and the horizontal surface if the acceleration of the block is 2.0 m/s2?
not 0.19
A 50-kg block is at rest on a 15o slope. A force of 250 N is acting on the block up the slope parallel to it. If the block does not slide up the slope, what is the minimum value of the coefficient of static friction between the block and the slope?
not 0.528
What is the gravitational force between two identical bodies with a mass of 2.0x104 kg each if they are 2.0 m apart?
not 1.2x10-7 N
The initial velocity of a truck is 10 m/s. How long must it accelerate at a constant acceleration of 2 m/s2 before its average velocity is equal to three times its initial velocity?
not 10 s
A 2000 kg car moving at 100 km/h crosses the top of a hill with a radius of curvature of 100 m. What is the normal force exerted by the seat on the driver if the mass of the driver is 60 kg?
not 100 N
The initial speed of a car is 25 m/s. The driver needs to overtake another car and accelerates at a rate of 0.58 m/s2 for 5.2 seconds. How far does his car travel during this time?
not 130 m
Two masses in the figure below rest on a smooth table. A force of 14 N is applied on A. What force does B exert on A?
not 14 N
If the speed of an object traveling in a circle is double, and the radius of the circle is halved, the centripetal acceleration of the object would increase by a factor of ___.
not 2
A stone is launched from the ground into the air so that the vertical component of the velocity is 20 m/s. It will hit the ground in ___.
not 2.04 s
A machine-gun is attached to a railroad car of a mass of 1.2x105 kg. How many of 0.020 kg bullets would have to be fired at 300 m/s off the back of the railroad car to give it a forward velocity of 1 m/s?
not 200
The work required to accelerate an object initially at rest to a speed v0 is W. What is the additional work needed to increase its speed from v0 to 2v0?
not 2W
A 40-kg crate is being pulled across a floor by a rope which exerts a force of 10 N at an angle of 35o above the horizontal. Find the normal force exerted by the floor.
not 398 N
The graph above shows velocity as a function of time t for a 0.50 kg object traveling along a straight line. The graph has three segments labeled 1, 2, and 3. A rope exerts a constant force of magnitude FT on the object along its direction of motion the whole time. During segment 2 only, a frictional force of magnitude Ff is also exerted on the object. For another identical object initially at rest, no frictional force is exerted during segment 2 (between t = 2 s and t = 4 s). A rope exerts the same constant force of magnitude FT as in the previous scenario. What is the change in the objects kinetic energy during segment 2?
not 4.00 J
A 2-kg softball is pitched to a player at 20 m/s. The player hits it back along the same path and at the same speed. If the bat was in contact with the ball for 0.1 s, the average force on the ball was:
not 400 N
A projectile is launched horizontally from a cliff with an initial speed of 40 m/s. The cliff is 125 m high and the projectile travels a horizontal distance of 200 m from the bottom of the cliff. What is the speed of the projectile right before it hits the ground?
not 56 m/s
A weight of 5000 N is suspended by two cables. The object is at rest. The first cable is horizontal and the second makes an angle of 143o with the first cable. Find the tension of the second cable.
not 6740 N
A boy pulls a 12-kg crate resting on a horizontal surface with a force that is 30o above the horizontal. What minimum force does he need to exert to start the crate moving if the coefficient of static friction is 0.40?
not 71 N
The escape velocity at the surface of Earth is 8 km/s. What is the escape velocity at the surface of a planet whose radius is 4 times and whose mass is 100 times that of Earth?
not 8 km/s
A cart slows with an acceleration of 2 m/s2 over a period of 6 s. If its initial speed was 12 m/s how far will it travel before it stops?
not 84 m
The radius of a planet is three times that of Earth and its mass is nine times that of Earth. The acceleration due to gravity on this planet is _________g.
not 9
Two bodies, masses m1 and m2, attract each other with force F. If one of the masses is doubled, the new gravitational force will be:
not F/4
A 15.2 kg mass has a gravitational potential energy of -342 J. How high from the ground is it?
not GPE cannot be negative
An object of a mass of 2.5-kg is launched upwards, from the ground, with an initial speed of 39 m/s. How fast is the object traveling just before it hits the ground? Assume that there is no air resistance.
not Greater than 39 m/s
Which of the following is true about momentum?
not It is a product of mass times velocity.
If no forces are acting on a moving object, the object will continue to move with constant
not None of these
A golf ball is launched from the ground with a speed of 1.141 m/s at 45° above the horizontal. What is its speed just before it strikes ground?
not None of these.
A bomber flying at a constant velocity in level flight releases its bomb and hits a target on the ground. Neglecting air resistance, which one of the following is NOT true?
not The horizontal velocity of the plane equals the horizontal velocity of the bomb when it hits the target.
Padded dashboards in cars are safer than non-padded ones because an occupant hitting the dash in an accident has:
not increased time of impact
In a completely elastic collision:
not momentum is conserved, but not kinetic energy.
In an inelastic collision, the final total momentum is _____
not more than the initial momentum
If a net impulse is applied to an object is not equal to zero, then ________.
not the impulse causes a change in momentum of the object
Impulse is ___________.
not the same as momentum
You bend your knees when you jump from an elevated position because:
not you are destroying energy
A rock is thrown at 50 degrees above the horizontal. As it rises, its horizontal component of velocity _____.
remains unchanged
The more powerful the motor is, the:
shorter the time interval for doing the work is
The word "normal" in the phrase "normal force" indicates that:
the force exerted by a surface is perpendicular to itself
Two skaters are pushing each other away. One skater's mass is 60 kg and the other skater's mass is 72 kg. As a result:
their momenta are equal but opposite.
Momentum of a system is conserved only when:
there are no external forces acting on the system
A large platform is initially at rest on a smooth surface. A dog on the platform starts running toward the east. The mass of the dog is one-half the mass of the platform. When the dog moves toward the east with a speed vo, the platform moves toward the ________ with a speed ________.
west ... vo/2
A car is moving up a hill at constant speed. Which statement below is correct?
work is being done by a non-conservative force
Work done by STATIC FRICTION is always:
zero
The earth rotates once in 24 hours about its axis. What is the rotational speed of the earth?
π/12 rad/hour
An object is thrown upward with an initial velocity of 32.1 m/s. What is its velocity in 4.0 s? (use g = 9.81 m/s2)
-7.14
An object is accelerating _____.
when its speed or direction changes
The horizontal and vertical components of the initial velocity of a projectile are 50 m/s and 120 m/s respectively. What is the magnitude of the initial velocity?
130 m/s
Two objects are thrown from the top edge of a cliff with a speed of 10 m/s. One object is thrown straight down and the other straight up. If the first object hits the ground in 4 s, the second hits the ground in _____ after the first object. (Let g = 10 m/s2)
2 s
Mike is serving the volleyball for the second time in a volleyball game. If the ball leaves his hand with twice the velocity it had on the first serve, its horizontal range R would be:
four times as much
A 5.0-kg block is pulled horizontally across a floor by a string attached to it with an acceleration of 2 m/s2. What is the tension in the string if the coefficient of sliding kinetic friction between the block and floor is 0.2?
19.8 N
A 4.4-kg mass is falling starting from rest at a height of 22 m. How much time does it take for the mass to reach the ground?
2.1 seconds
Suppose with 200 N of force applied horizontally to your 1500 N refrigerator that it slides across your kitchen floor at a constant velocity. What are the friction forces on the refrigerator?
200 N
The coefficient of static friction between the tires of a car and asphalt is 0.77 . What is the steepest angle of a slope on which the car can be parked?
37o
A stone is thrown horizontally from the top of a cliff. Ignoring air resistance, the forces acting on the stone as it falls are:
gravity alone
A basketball player throws a ball at an angle of 30° above the horizontal. At what point does the magnitude of the acceleration reach a minimum?
not just after leaving the player's hand
A person weighing 823 N is standing on a scale in an elevator that is accelerating upward at 4 m/s2. What does the scale read?
not none of the above
If a 4-kg object is being pushed with the same force as another object that has a mass of 10-kg, then:
not the 10-kg object accelerates 2.5 times faster than the 4-kg object
A crate is attracted toward the center of the earth by a gravitational force of 500 N. The force with which the earth is attracted toward the crate is:
not very small
When the object in the question above reaches it maximum height, it is true of the acceleration, a, and the velocity, v, that:
velocity is equal to zero, but acceleration is not
