Chapter 7 Homework

A cue ball strikes a glancing blow against a second billiard ball initially at rest. Which of the following sketches correctly depicts the velocities of the billiard balls after the collision?

(figure)

Two lumps of clay traveling through the air in the opposite directions collide and stick together. Their momentum vectors prior to the collision are shown in the diagram. Which of the following illustrations shows the correct combined lump of clay's momentum?

(one with the arrow to the right)

A ball traveling with an initial momentum of 1.8 kg·m/s bounces off a wall and comes back in the opposite direction with a momentum of -1.8 kg·m/s. What is the impulse required to produce this change? The impulse required to produce this change is _____ Ns

-3.6 Ns

A ball traveling with an initial momentum of 1.8 kg·m/s bounces off a wall and comes back in the opposite direction with a momentum of -1.8 kg·m/s. Determine the change in momentum of the ball. The change in momentum of the ball is ____ kg. m/s

-3.6 kg. m/s

A railroad car with a mass of 13000 kg collides and couples with a second car of mass 20000 kg that is initially at rest. The first car is moving with a speed of 3.5 m/s prior to the collision. If external forces are ignored, what is the final velocity of the two railroad cars after they couple? The final velocity of the cars is ____ m/s

1.38 m/s

A rifle with a mass of m1 = 3.4 kg fires a bullet with a mass of 7.9 g (0.0079 kg). The bullet moves with a velocity of 860 m/s after the rifle is fired. If external forces acting on the rifle can be ignored, what is the magnitude of the recoil velocity of the rifle? The magnitude of the recoil velocity of the rifle is ____ m/s

2 m/s

An average force of 4800 N acts on a golf ball for a time interval of 0.007 s. What is the magnitude of the impulse acting on the golf ball? The magnitude of the impulse acting on the golf ball is ___Ns

33.6 Ns

An average force of 4800 N acts on a golf ball for a time interval of 0.007 s. Determine the change in the momentum of the golf ball. The change in the momentum of the golf ball is _____kg. m/s

33.6 kg. m/s

A fullback with a mass of 108 kg and a velocity of 3.2 m/s due north collides head-on with a defensive back with a mass of 79 kg and a velocity of 5.6 m/s due south. Calculate the initial momentum of the each player. _____kg·m/s north and ______kg.m/s south

345.6 and 442.4

A ball experiences a change in momentum of 68 kg·m/s. If the time of interaction is 0.15 s, what is the magnitude of the average force acting on the ball? Round the final answer to the nearest whole number. The magnitude of the average force acting on the ball is ____N

453.3

A railroad car with a mass of 13000 kg collides and couples with a second car of mass 20000 kg that is initially at rest. The first car is moving with a speed of 3.5 m/s prior to the collision. Determine the initial momentum of the first car. The initial momentum of the first car is _____ kg.m/s

45500 kg. m/s

A rifle with a mass of m1 = 3.4 kg fires a bullet with a mass of 7.9 g (0.0079 kg). The bullet moves with a velocity of 860 m/s after the rifle is fired. What is the momentum of the bullet after the rifle is fired? The momentum of the bullet after the rifle is fired is ______ kg. m/s

6.8 kg. m/s

A ball experiences a change in momentum of 68 kg·m/s. What is the magnitude of the impulse acting on the ball? The impulse acting on the ball is _____ Ns

68

A fullback with a mass of 108 kg and a velocity of 3.2 m/s due north collides head-on with a defensive back with a mass of 79 kg and a velocity of 5.6 m/s due south. What is the total momentum of the system before the collision? The total momentum of the system before the collision is

96.8

A compact car and a large truck have a head-on collision. During the collisions, which vehicle, if either, experiences: the greater change in momentum

both experience the same change in momentum

A compact car and a large truck have a head-on collision. During the collisions, which vehicle, if either, experiences: the greater force of impact

both experience the same force

A compact car and a large truck have a head-on collision. During the collisions, which vehicle, if either, experiences: the greater impulse

both experience the same impulse

Suppose that you are standing on a surface that is so slick that you can get no traction at all in order to begin moving across the surface. Fortunately you are carrying a bag of oranges. How can you get yourself moving to the right?

by throwing the oranges to the left

A railroad car collides and couples with a second railroad car that is standing still, and the two stick together. What type of collision is it?

completely inelastic

A cue ball strikes an eight ball of an equal mass, initially at rest. The cue ball stops and the eight ball moves forward with a velocity equal to the initial velocity of the cue ball. What type of collision is this?

elastic

If a ball bounces off a wall so that its velocity coming back has the same magnitude that it had prior to bouncing, in what direction, if any, is the impulse from the wall on the ball?

in the same direction as the ball's final velocity

If you catch a baseball or softball with your bare hand, how, if at all, will the force exerted on the ball change if you pull your arm back during the catch?

it will decrease the force

If a ball bounces off a wall so that its velocity coming back has the same magnitude that it had prior to bouncing, how has the momentum of the ball changed?

its direction has changed

What is the advantage of an airbag in reducing injuries during collisions?

longer contact time

A ball bounces off a wall with a velocity whose magnitude is less that it was before hitting the wall. What type of collision is this?

partially inelastic

A fullback with a mass of 108 kg and a velocity of 3.2 m/s due north collides head-on with a defensive back with a mass of 79 kg and a velocity of 5.6 m/s due south. If they stick together and external forces can be ignored, what direction will they be traveling immediately after they collide? If they stick together and if external forces are ignored, they will be traveling due _____ immediately after the collision

south

A compact car and a large truck have a head-on collision. During the collisions, which vehicle, if either, experiences: the greater acceleration

the compact car

Two shotguns are identical in every respect (including the size of the shell fired) except that one has twice the mass of the other. Which gun, if either, will tend to recoil with greater velocity when fired?

the lighter one

Two objects collide under conditions where total momentum is conserved. Is the momentum conserved for each object?

the momentum of each object is not conserved separately

A car and a small truck traveling at right angles to each other with the same speed collide and stick together. The truck's mass is roughly twice the car's mass. The final velocity vector of the system will be closer to the original direction of which, if either, vehicle?

the truck

A truck and a bicycle are moving side by side with the same velocity. Which, if either, will require the larger impulse to bring it to a halt?

the truck

A railroad car collides and couples with a second railroad car that is standing still. If the external forces acting on the system are ignored, how is the velocity of the system after the collision compared with before the collision?

the velocity will decrease

Two ice skaters, initially at rest push off one another. What sign is the total momentum of the system after they push off?

zero