AP Physics Chapter 6 Review

A 20 kg object sitting at rest is struck elastically in a head on collision with a 10 kg object initially moving at +3.0 m/s. Find the final velocity of the 20 kg object after the collision

+2.0 m/s

Two identical 7-kg bowling balls roll toward each other. The one on the left is moving at +4 m/s while the one on the right is moving at −4 m/s. What is the velocity of each ball after they collide elastically?

-4 m/s, +4 m/s

A 0.10-kg object moving initially with a velocity of +0.20 m/s makes an elastic head-on collision with a 0.15-kg object initially at rest. What percentage of the original kinetic energy is retained by the 0.10-kg object?

-4%

A 20-g bullet moving at 1 000 m/s is fired through a one-kg block of wood emerging at a speed of 100 m/s. What is the change in the kinetic energy of the bullet-block system as a result of the collision assuming the block is free to move?

-9.7 kJ

A billiard ball is moving in the x-direction at 30 cm/s and strikes another billiard ball moving in the y-direction at 40 cm/s. As a result of the collision, the first ball moves at 50 cm/s and the second ball stops. What is the change in kinetic energy of the system as a result of the collision?

0

Two skaters, both of mass 75 kg, are on skates on a frictionless ice pond. One skater throws a 0.3-kg ball at 5 m/s to his friend, who catches it and throws it back at 5 m/s. When the first skater has caught the returned ball, what is the velocity of each of the two skaters?

0.04 m/s, moving apart

A 20-g bullet moving at 1 000 m/s is fired through a one-kg block of wood emerging at a speed of 100 m/s. What is the kinetic energy of the block that results from the collision if the block had not been moving prior to the collision and was free to move?

0.16 kJ

A 75-kg swimmer dives horizontally off a 500-kg raft. If the diver's speed immediately after leaving the raft is 4 m/s, what is the corresponding raft speed?

0.6 m/s

A model car is propelled by a cylinder of carbon dioxide gas. The cylinder emits gas at a rate of 4.5 g/s with an exit speed of 80.0 m/s. The car has a mass of 400 g, including the CO2 cylinder. Starting from rest, what is the car's initial acceleration?

0.90 m/s^2

A cannon of mass 1 500 kg fires a 10-kg shell with a velocity of 200 m/s at an angle of 45° above the horizontal. Find the recoil velocity of the cannon across the level ground.

0.94 m/s

A uranium nucleus ( mass 238 units ) at rest decays into helium nucleus ( mass 4.0 units) and thorium nucleus ( mass 234 units ). If the speed of the helium nucleus is 6.0 x 10^5 m/s, what is the speed of the thorium nucleus?

1.0 x 10^4

A 2 500-kg truck moving at 10.00 m/s strikes a car waiting at a traffic light, hooking bumpers. The two continue to move together at 7.00 m/s. What was the mass of the struck car?

1070 kg

A miniature spring loaded, radio controlled gun is mounted on an air puck. The gun's bullet has a mass of 0.005 kg and the gun and puck have a combined mass of 0.120 kg. With the system initially at rest, the radio controlled trigger releases the bullet causing the puck and empty gun to move with a speed of 0.5 m/s. what is the bullet´s speed?

12.0 m/s

A 75-kg swimmer dives horizontally off a 500-kg raft. The diver's speed immediately after leaving the raft is 4.0 m/s. A micro-sensor system attached to the edge of the raft measures the time interval during which the diver applies an impulse to the raft just prior to leaving the raft surface. If the time interval is read as 0.20 s, what is the magnitude of the average horizontal force by diver on the raft?

1500 N

A 90kg halfback running north with a speed of 10 m/s is tackled by a 120 kg opponent running south at 4 m/s. The collision is perfectly inelastic. Compute the velocity of the two players just after tackle.

2 m/s north

A 0.12-kg ball is moving at 6 m/s when it is hit by a bat, causing it to reverse direction and have a speed of 14 m/s. What is the change in the magnitude of the momentum of the ball?

2.4 kg⋅m/s

A billiard ball (ball #1) moving at 5 m/s strikes a stationary ball (ball #2) of the same mass. After the collision, ball #1 moves at a speed of 4.35 m/s. Find the speed of ball #2 after the collision.

2.47 m/s

Lonnie pitches a baseball of mass 0.20 kg. The ball arrives at home plate with a speed of 40 m/s and is batted straight back to Lonnie with a return speed of 60 m/s. If the bat is in contact with the ball for 0.050 s, what is the impulse experienced by the ball?

20 N⋅s

Jerome pitches a baseball of mass 0.20 kg. The ball arrives at home plate with a speed of 40 m/s and is batted straight back to Jerome with a return speed of 60 m/s. What is the magnitude of change in the ball's momentum?

20 kg⋅m/s

A rocket of total mass M and with burnout mass 0.20 M attains a speed of 2300 m/s after starting from rest in deep space. What is the exhaust velocity of the rocket?

2000 m/s

A baseball infielder, mass 75.0 kg, jumps up with velocity 3.00 m/s and catches a 0.150 kg baseball moving horizontally at 50.0 m/s.Of the following, which is closest to the final momentum of the system, infielder, and baseball?

225 kg⋅m/s

A helicopter stays aloft by pushing large quantities of air downward every second. What mass of air must be pushed downward at 40.0 m/s every second to keep a 1000 kg helicopter aloft?

245 kg

Mitch throws a 100-g lump of clay at a 500-g target, which is at rest on a horizontal surface. After impact, the target, including the attached clay, slides 2.1 m before stopping. If the coefficient of friction is µ = .50, find the speed of the clay before impact.

27 m/s

During a snowball fight two balls with masses of 0.4 and 0.6 kg, respectively, are thrown in such a manner that they meet head-on and combine to form a single mass. The magnitude of initial velocity for each is 15 m/s. What is the speed of the 1.0-kg mass immediately after collision?

3 m/s

At liftoff, the engines of the Saturn V rocket consumed 13000 kg/s of fuel and exhausted the combustion products at 2900 m/s. What was the total upward force (thrust) provided by the engines?

3.77 x 10^7

Ann the Astronaut weighs 60 kg. She is space walking outside the space shuttle and pushes a 350-kg satellite away from the shuttle at 0.90 m/s. What speed does this give Ann as she moves toward the shuttle?

5.3 m/s

A 7.0-kg bowling ball strikes a 2.0-kg pin. The pin flies forward with a velocity of 6.0 m/s; the ball continues forward at 4.0 m/s. What was the original velocity of the ball?

5.7 m/s

A machine gun is attached to a railroad flatcar that rolls with negligible friction. If the railroad car has a mass of 6.25 × 10^4 kg, how many bullets of mass 25 g would have to be fired at 250 m/s off the back to give the railroad car a forward velocity of 0.5 m/s?

5000

Alex throws a 0.15-kg rubber ball down onto the floor. The ball's speed just before impact is 6.5 m/s, and just after is 3.5 m/s. What is the change in the magnitude of the ball's momentum?

60 N

A crane drops a 0.30 kg steel ball onto a steel plate. The ball's speeds just before impact and after are 4.5 m/s and 4.2 m/s, respectively. If the ball is in contact with the plate for 0.030 s, what is the magnitude of the average force that the ball exerts on the plate during impact?

87 N

A miniature, spring-loaded, radio-controlled gun is mounted on an air puck. The gun's bullet has a mass of 5.00 g, and the gun and puck have a combined mass of 120 g. With the system initially at rest, the radio-controlled trigger releases the bullet, causing the puck and empty gun to move with a speed of 0.500 m/s. Of the total kinetic energy of the gun-puck-bullet system, what percentage is in the bullet?

96%

Three satellites are launched into space connected together. Once in deep space, an explosive charge separates the three satellites and they move apart. The satellites each have different masses with m1<m2<m3. Which of the following statements is always true?

Although one or more of the above statements could be true in special cases, they are not always true

A billiard ball collides in an elastic head-on collision with a second stationary identical ball. After the collision which of the following conditions applies to the first ball?

Comes to rest

Neglecting gravity, doubling the exhaust velocity from a single stage rocket initially at rest changes the final kinetic energy of the burnout stage by what factor? Assume all other variables, such as the mass of the rocket and the mass of the fuel, do not change.

It quadruples

Two masses m1 and m2, with m1<m2, have momenta with equal magnitudes. how do their kinetic energies compare?

KE1>KE2

The dimensional equivalent of the quantity "momentum" in terms of the fundamental quantities (mass, length, time) is which of the following?

MLT-1

The dimensional equivalent of the quantity impulse in terms of the fundamental quantities (mass, length, time) is which of the following?

MLT-1

In a two-body collision, if the momentum of the system is conserved, then which of the following best describes the kinetic energy after the collision?

May also be conserved

The impulse experienced by a body is equivalent to the body's change in:

Momentum

If the momentum of an object is tripled, its kinetic energy will change by what factor

Nine

A high diver of mass 70.0 kg jumps off a board 10.0 m above the water. If, 1.0 s after entering the water his downward motion is stopped, what average upward force did the water exert?

No answer is correct

Two masses collide and stick together. Before the collision of one of the masses was at rest. Is there a situation in which the kinetic energy is conserved in such a collision?

No, kinetic energy is always lost in such a collision

Two particles collide, one of them initially being at rest. Is it possible for both particles to be at rest after the collision?

No.

Object 1 has twice the mass of Object 2. Both objects have the same kinetic energy. Which of the following statements is true?

Object 1 has a momentum of greater magnitude than Object 2

Object 1 has twice the mass of Object 2. Each of the objects has the same magnitude of momentum. Which of the following statements is true?

One object has twice the kinetic energy of the other

A lump of clay is thrown at a wall. A rubber ball of identical mass is thrown with the same speed toward the same wall. Which statement is true?

The ball experiences a greater change in momentum than the clay

Neglecting gravity, doubling the exhaust velocity from a single stage rocket initially at rest changes the final velocity attainable by what factor? Assume all other variables, such as the mass of the rocket and the mass of the fuel, do not change.

The final velocity doubles

An object of mass m moving at speed v0 strikes an object of mass 2m which had been at rest. The first object bounces backward along its initial path at speed v0. Is this collision elastic, and if not, what is the change in kinetic energy of the system?

The kinetic energy increases by mv^2

Two objects, one less massive than the other, collide elastically and bounce back after the collision. If the two originally had velocities that were equal in size but opposite in direction, then which one will be moving faster after the collision?

The less massive one

A tennis ball is held above and in contact with a basketball, and then both are simultaneously dropped. The tennis ball bounces off the basketball at a fairly high speed. This is because:

The massive basketball transfers momentum to the lighter tennis ball

In an automobile collision, how does an airbag lessen the blow to the passenger? Assume as a result of the collision, the passenger stops

The stopping impulse is the same for either the hard objects or the airbag. Unlike the windshield or dashboard, the air bag gives some increasing the time for the slowing process and thus decreasing the average force on the passengers.

If a glass of water is on a table with a piece of paper under it, it is relatively easy to pull the paper out without disturbing the glass very much if the pull is done very quickly. This is because, with a quick pull:

The time for the pull will be less

A billiard ball is moving in the x-direction at 30 cm/s and strikes another billiard ball moving in the y-direction at 40 cm/s. As a result of the collision, the first ball moves at 50 cm/s and the second ball stops. In what direction does the first ball move?

at an angle of 53.1 ccw from the x-direction

A 5-kg object is moving to the right at 4 m/s and collides with another object moving to the left at 5 m/s. The objects collide and stick together. After the collision, the combined object:

has less momentum than the system had before the collision

A valid unit for momentum is which of the following

kg⋅m/s

The units of impulse are equivalent to:

kg⋅m/s

If a two-body collision is not head-on, then we may always assume that:

momentum is conserved

In a two-body collision, if the kinetic energy of the system is conserved, then which of the following best describes the kinetic energy after the collision?

must also be conserved

2. A model rocket sits on the launch pad until its fuel is ignited, blasting the rocket upward. During the short time of blast-off, as the ignited fuel goes down, the rocket goes up because:

of none of the above reasons

In a partially elastic collision between two objects with unequal mass:

the momentum of one will increase by the amount that the momentum of the other decreases

When a collision is perfectly inelastic, then:

the participants stick together

In a system with two moving objects, when a collision occurs between the objects

the total momentum is always conserved

Two masses m1 and m2, with m1 = 3m2, undergo a head-on collision. If the particles were approaching with speed v before the collision, with what speed are they moving apart after collision?

v

A ball with original momentum +4.0 kg⋅m/s hits a wall and bounces straight back without losing any kinetic energy. The change in momentum of the ball is:

−8.0 kg⋅m/s