PHYSICS FINAL QUIZ5

A 30-kg girl and a 25-kg boy face each other on friction-free roller blades. The girl pushes the boy, who moves away at a speed of 1.0 m/s. The girl's speed is?

0.83m/s

A 1-kg chunk of putty moving at 1 m/s collides with and sticks to a 5-kg bowling ball that is initially at rest. The bowling ball and putty are then set in motion with a speed of?

1/6m/s

A car moves four times as fast as an identical car. Compared to the slower car, the faster car has?

16 times the KE

If you exert 1N for a distance of 1m in 1s, you will deliver a power of?

1W

A rifle of mass 2 kg is suspended by strings. The rifle fires a bullet of mass 1/100 kg at a speed of 200 m/s. The recoil velocity of the rifle is about?

1m/s

A 2-kg mass has 40 J of potential energy with respect to the ground. Approximately how far is it located above the ground?

2m

A 2-kg mass is held 4 m above the ground. What is the approximate potential energy of the mass with respect to the ground?

80J

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

about 10 times

Consider driving into a massive concrete wall with no "give," versus having a head-on collision at the same speed with an identical car moving toward you at the same speed. It would be more damaging to hit the?

both the same

A cannon recoils from firing a cannonball. The speed of the cannons recoil is small because?

cannon has more mass than the ball

A bullet fired from a gun. The speed of the bullet will be about the same as the speed of the recoiling gun?

if the mass of the bullet equals the mass of gun

When a car breaks to a stop its kinetic energy is transformed?

into heat energy

Two objects, A and B, have the same size and shape but A is twice and heavy as B. When they are dropped simultaneously from a tower, they reach the ground at the same time, but A has greater?

momentum

If the speed of a moving object doubles then?

momentum doubles

An object that has kinetic energy must be?

moving

If you push for an hour against a stationary wall, no work is done?

on the wall

A 50-kg sack is lifted 2 m in the same time as a 25-kg sack is lifted 4 m. The power expended in raising the 50-kg sack compared to the power used to lift the 25-kg sack is?

the same

If you push an object with twice the work input for twice the time, your power input is?

the same amount as for half the work in half the time

In order 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 upon impact. Doing this reduces the force of impact on the player's hand principally because the?

time of impact is increased

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?

twice

An object is raised about the ground gaining a certain amount of potential energy. If the same object is raised twice as high, it gains?

twice as much potential energy

If you push an object just as far while applying twice the force, you do?

twice as much work