Physics 5

Which would produce more force: driving into a very massive concrete wall with no "give," or having a head-on collision at the same speed with an identical car moving toward you with the same speed?

both the same.

A freight train rolls along a track with considerable momentum. If it rolls at the same speed but has twice as much mass, its momentum is-

doubled.

According to the impulse-momentum equation Ft = change in (mv), a person will suffer less injury falling on a wooden floor which "gives" than on a more rigid cement floor. The "F" in the above equation stands for the force exerted on the-

either the force on the person or the force on the floor.

A heavy truck and a small car rolling down a hill at the same speed are forced to stop in the same amount of time. Compared to the force that stops the car, the force needed to stop the truck is-

greater.

A karate expert executes a swift blow and breaks a cement block with her bare hand. The magnitude of the force experienced by her hand is-

identical to the force applied to the block.

When you are in the way of a fast-moving object and can't get out of its way, you will suffer a smaller force of impact if you decrease its momentum over a-

long time.

Two objects have the same size and shape, but one is much heavier than the other. When they are dropped simultaneously from a tower, they reach the ground at the same time, but the heavier one has a greater-

momentum.

A large metal ball is shot from a cannon with a short barrel. If the same ball were to be shot from cannon with a longer barrel, its muzzle velocity would be-

more.

A rifle recoils while firing a bullet. The speed of the rifle's recoil is small because the-

rifle has much more mass than the bullet.

Compared to falling on a stone floor, a wine glass may not break when it falls on a carpeted floor because the-

stopping time is longer on the carpet.

It is correct to say that impulse is equal to-

the change in momentum it produces.

The force on an apple hitting the ground depends upon-

the time of impact with the ground. the speed of the apple just before it hits. whether or not the apple bounces.

To catch a ball, a baseball player extends the hand forward before impact with the ball and then lets it ride backward in the direction of the ball's motion. Doing this reduces the force of impact on the player's hand principally because the-

time of impact is increased.

Two billiard balls having the same mass and speed roll toward each other. What is their combined momentum after they meet?

0

A 1-kg chunk of putty moving at 1 m/s collides with and sticks to a 5-kg bowling ball initially at rest. The bowling ball and putty then move with a momentum of-

1 kg m/s.

A ball is moving at 3 m/s and has a momentum of 48 kg m/s. What is the ball's mass?

16 kg.

A 5000-kg freight car moving at 2 m/s runs into a 10,000-kg freight car at rest. They couple upon collision and move away as one body at-

2/3 m/s.

A 4 kg ball has a momentum of 12 kg m/s. What is the ball's speed?

3 m/s.

Which of the following has the largest momentum relative to the Earth's surface?

a pickup truck speeding along a highway.

When you jump from an elevated position you usually bend your knees upon reaching the ground. By doing this, you make the time of the impact about 10 times as great as for a stiff-legged landing. In this way the average force your body experiences is-

about 1/10 as great.