Physical Science

Two billiard balls having the same mass roll toward each other at the same speed. What is the net momentum of the two-ball system?

0 kg•m/s

Two identical freight cars roll without friction towards each other on a level track. One car rolls at 2 m/s and the other car rolls at 1 m/s. After the cars collide, they couple and roll together with a speed of

0.5 m/s

A 1000-kg truck moving at 10 m/s that brakes to a stop in 5 s has an average braking force of

2000 N

A 5000-kg freight car crashes into a 10,000-kg freight car at rest. They couple upon collision and move with a speed of 2 m/s. What was the initial speed of the 5000-kg freight car?

6 m/s

A boxer punches a sheet of paper in midair from rest to a speed of 40 m/s in 0.05 s. If the mass of the paper is 0.01 kg, the force of the punch on the paper is

8.0 N

The impulse-momentum relationship is a direct result of

Second Law

Which has more momentum after firing, the cannonball or the recoiling cannon?

They are both the same

When you jump from an elevated position you usually bend your knees upon reaching the ground. By doing this, the contact time is about 10 times more than for a stiff-legged landing and the average force your body experiences is reduced by

about 10 times.

While driving down the highway a lovebug spatters onto your windshield. Which undergoes the greater impulse?

both the same

While driving down the highway a lovebug spatters onto your windshield. Which experiences the greater force of impact?

both the same but with different consequences

When you can't escape being hit by a fast-moving object, you'll suffer a smaller force if the collision time is

long

Compared with falling on a wooden floor, a wine glass may not break when it falls on a carpeted floor because of

longer time to stop.

When a cannon fires a cannonball at a given speed, the smaller recoil speed of the cannon is due to differences in

masses

A heavy truck and a small truck roll down a hill. Neglecting friction, at the bottom of the hill the heavy truck has greater

momentum

It is correct to say that impulse is equal to

the change in momentum.

To catch a fast-moving softball with your bare hand, you extend your hand forward just before the catch and then let the ball ride backward with your hand. Doing this reduces the catching force because the

time of catch is increased.

The distinction between impulse and force involves the

time the force acts.