Physics Chapter 6

A ball with a mass of 0.15 kg and a velocity of 5.0 m/s strikes a wall and bounces straight back with a velocity of 3.0 m/s. What is the change in momentum of the ball?

-1.20 kg•m/s -> deltap = m(vf-vi)

A 6.0 x 10^-2 kg tennis ball moves at a velocity of 12 m/s. The ball is struck by a racket, causing it to rebound in the opposite direction at a speed of 18 m/s. What is the change in the ball's momentum?

-1.8 kg m/s -> deltap = m(vf-vi)

A ball with a momentum of 4.0 kg m/s hits a wall and bounces straight back without losing any kinetic energy. What is the change in the ball's momentum?

-8.0 kg m/s

A 0.10 kg object makes an elastic head-on collision with a 0.15 kg stationary object. The final velocity of the 0.10 kg object after the collision is-0.045 m/s, and the final velocity of the 0.15 kg object after the collision is 0.16 m/s. What was the initial velocity of the 0.10 kg object?

0.20 m/s —> v1,i = (m1v1f + m2v2f) - (m2v2i) / m1

An astronaut with a mass of 85 kg is outside a space capsule when the tether line breaks. To return to the capsule, the astronaut throws a 2.0 kg wrench away from the capsule at a speed of 14 m/s. At what speed does the astronaut move toward the capsule?

0.33 m/s —> v1,f= -m2v2,f/m1

A 90 kg halfback runs north and is tackled by a 120 kg opponent running south at 4 m/s. The collision is perfectly inelastic. Just after the tackle, both players move at a velocity of 2 m/s north. Calculate the velocity of the 90 kg player just before the tackle.

10 m/s to the north—> v1i= - (m1 + m2)vf-m2v2i/m1

Each croquet ball in a set has a mass of 0.50 kg. The green ball travels at 10.5 m/s and strikes a stationary red ball. If the green ball stops moving, what is the final speed of the red ball after the collision?

10.5 m/s

A 0.2 kg baseball is pitched with a velocity of 40 m/s and is then batted to the pitcher with a velocity of 60 m/s. What is the magnitude of change in the ball's momentum?

20 kg*m/s -> deltap = m(vf-vi)

What velocity must a 1340 kg car have in order to have the same momentum as a 2680 kg truck traveling at a velocity of 15 m/s to the west?

3.0 m/s west -> v2= m1v1/m2

A train with a mass of 1.8 x 10^3 kg is moving at 15 m/s when the engineer applies the breaks. If the braking force is constant at 3.5x10^4 N, how long does it take the train to stop? How far does the train travel during this time?

77s ; 5.8 x 10^2 m —> m(vf-vi) / F ; —> delta (x)= 1/2(vf+vi)delta (t)

Which of the following statements properly relates the variable in the equation Fdelta(t)=delta(p)

A large constant force acting over a long time interval causes a large change in momentum

If a force is exerted on an object, which statement is true?

A small force applied over a long time interval can produce a large change in the object's momentum.

How can a small force produce a large change in momentum?

A small force can produce a large change in momentum if the force acts on an object for a long period of time.

When comparing the momentum of two moving objects, which of the following is correct?

C. The less massive object will have less momentum if the velocities are the same.

Why is the sound produced by a collision evidence that the collision is not perfectly elastic?

It can't conserve kinetic energy since it loses some to create the sound.

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

Momentum

Which of the following statements about the conservation of momentum is not correct?

Momentum is not conserved for a system of objects in a head-on collision.

As a bullet travels through the air, it slows down due to air resistance. How does the bullet's momentum change as a result?

The bullet's momentum decreases as its speed decreases.

A child with a mass of 23 kg rides a bike with a mass of 5.5 kg at a velocity of 4.5 m/s to the south. Compare the momentum of the child with the momentum of the bike.

The child has a greater momentum than the bike.

A baseball pitcher's first pitch is a fastball, moving at a high speed. The pitcher's second pitch -with the same ball- is a change up, moving more slowly. Which pitch is harder for the catcher to stop?

The first pitch is harder to stop. It has a greater momentum because is has a greater velocity.

A student walks to class at a velocity of 3 m/s. To avoid walking into a door as it opens, the student slows to a velocity of 0.5 m/s. Now late for class, the student runs down the corridor at a velocity of 7 m/s. At what point in this scenario does the student have the least momentum?

The student has the least momentum when dodging the opening door

Compare the momentum of a 6160 kg truck moving at 3.00 m/s to the momentum of a 1540 kg car moving 12.0 m/s.

They have the same momentum p1=p2

A moderate force will break an egg. Using the concepts of momentum, force, and time interval, explain why an egg is more likely to break when it is dropped on concrete than if it is dropped on grass.

To stop a falling egg you'll need to change the momentum from its value at the time of impact to zero. It it hits the concrete, the time interval would be really small, so the force would be larger. If it lands on grass, the time interval would be larger, making the force smaller.

Is it possible for a spaceship traveling with constant velocity to experience a change in momentum?

Yes, if it's mass changed

Two billiard balls of equal mass are traveling straight toward each other with the same speed. They meet head-on in an collusion. What's the total momentum of the system containing the two balls before the collision?

Zero

Which of the following has the greatest momentum?

a tortoise with a mass of 275 kg moving at a velocity of 0.55 m/s

A 75 kg person walking around a corner bumped into an 80 kg person who was running around the same corner. The momentum of the 80 kg person

decreased

Two billiard balls collide. Identify the type of collision.

elastic

A roller coaster climbs up a hill at 4 m/s and then zips down the hill at 30 m/s. The momentum of the roller coaster

is greater down the hill than up the hill

A billiard ball collides with a stationary identical billiard ball in an elastic head-on collision. After the collision, which of the following is true of the first ball?

it comes to rest

In a two-body collision

momentum is always conserved

Which of the following best describes the momentum of two bodies after a two-body collision if the kinetic energy of the system is conserved?

must also be conserved

Two balls of dough collide and stick together. Identify the type of collision.

perfectly inelastic

Two objects stick together and move with a common velocity after colliding. Identify the type of collision.

perfectly inelastic

Two objects with different masses collide and bounce back after an elastic collision. Before the collision, the two objects were moving at velocities equal in magnitude but opposite in direction. After the collision,

the less massive object had gained momentum

In an inelastic collision between two objects with unequal masses,

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

The law of conservation of momentum states that

the total momentum of all objects interacting with one another remains constant regardless of the nature of the forces between the objects

Two skaters stand facing each other. One skater's mass is 60 kg, and the other's mass is 72 kg. If the skaters push away from each other without spinning,

their momenta are equal but opposite

Two swimmers relax close together on air mattresses in a pool. One swimmer's mass is 48 kg, and the other's mass is 55 kg. If the swimmers push away from each other,

their momenta are equal but opposite

A person sitting in a chair with wheels stands up, causing the chair to roll backward across the floor. The momentum of the chair

was zero while stationary and increased when the person stood