Physics Chapter 6 Homework

The impulse-momentum relationship is a direct result of A. Newton's 2nd law. B. Newton's law of gravity. C. Newton's 3rd law. D. Newton's 1st law.

A. Newton's 2nd law.

When you jump from an elevated position you usually bend your knees upon reaching the ground, which makes the time of the contact about 10 times that of a stiff-legged landing. In this way the average force your body experiences is A. about 1/10 as great. B. less than 1/10 as great. C. more than 1/10 as great. D. about 10 times as great.

A. about 1/10 as great.

A 5-kg shark swimming at 1 m/s swallows an absent-minded 1-kg fish swimming toward it at 4 m/s. The speed of the shark after his meal is A. 1/5 m/s. B. 1/2 m/s. C. 3/2 m/s. D. 1/6 m/s. E. 2/3 m/s.

D. 1/6 m/s.

The greater efficiency achieved with the curved blades of a Pelton wheel is due to A. bouncing. B. rotational momentum. C. greater time of water impact. D. divided impulse.

A. bouncing.

An open freight car rolls friction free along a horizontal track in a pouring rain that falls vertically. As water accumulates in the car, the car's speed A. decreases. B. doesn't change. C .increases. D. need more information

A. decreases.

When Freddy Frog drops vertically from a tree onto a horizontally-moving skateboard, the speed of the skateboard A. decreases. B. increases. C. neither decreases nor increases.

A. decreases.

A softer landing occurs when an falling object bounces from a surface A. in an extended time. B. quickly. C. either of these D. neither of these

A. in an extended time.

Padded dashboards in cars are safer in an accident than non-padded ones because passengers hitting the dashboard encounter lower impact forces due to the A. longer time of contact. B. decreased impulse. C. increased momentum. D. shorter time of contact.

A. longer time of contact.

A same-size iron ball and wooden ball are dropped simultaneously from a tower and reach the ground at the same time. The iron ball has a greater A. momentum. B. speed. C. acceleration. D. all of the above E. none of the above

A. momentum.

Two identical objects in outer space, one moving at 2 m/s, the other at 1 m/s, have a head-on collision and stick together. Their combined speed after the collision is A. 1.0 m/s. B. 0.5 m/s. C. 0.33 m/s. D. 0.67 m/s. E. none of the above

B. 0.5 m/s.

A bungee jumper attains a speed of 30 m/s just as the bungee cord begins to stretch. If the period of stretch is 2 s while coming to a halt, the jumper's average deceleration is about A. 0.5 g. B. 1.5 g. C. 2 g. D. g.

B. 1.5 g.

The conservation of momentum is most closely related to A. Newton's 1st law. B. Newton's 3rd law. C. Newton's law of gravity D. Newton's 2nd law.

B. Newton's 3rd law.

If several balls are thrown straight up with different initial speeds, the quantity that will have the same value along their paths is their A. maximum height. B. acceleration. C. initial momentum. D. time of travel. E. none of the above

B. acceleration.

Which produces more force: driving into a very massive concrete wall with no "give," or having a head-on collision with an identical car moving toward you at the same speed? A. car B. both the same C. wall D. need more information

B. both the same

When bullets are fired from an airplane in the forward direction, the momentum of the airplane is A. unchanged. B. decreased. C. increased.

B. decreased.

If you can't avoid being hit by a fast-moving object, you'll suffer a smaller contact force if you can extend that force over a A. both the same B. longer time. C. shorter time. D. shorter time.

B. longer time.

Two identical freight cars roll without friction (one at 1 m/s, the other at 2 m/s) toward each other on a level track. They collide, couple together, and roll away in the direction of A. the slower car. B. the faster car. C. neither, for they stop.

B. the faster car.

When a vertically falling firecracker bursts, the vector sum of momentum fragments A. in the vertical direction equals the momentum of the firecracker before bursting. B. in the horizontal direction cancels to zero. C. both of these D. neither of these

C. both of these

Which has the greater momentum when moving? A. a bullet B. a container ship C. either of these depending on speed

C. either of these depending on speed

The force that accelerates a rocket in outer space is exerted on the rocket by the A. rocket's wings. B. rocket's nose cone. C. exhaust gases. D. atmospheric pressure. E. none of the above

C. exhaust gases.

The total momentum of a flock of identical birds could be zero only if the birds are A. very tired and coming down to rest. B. flying in the same direction. C. flying in different directions. D. taking off from the ground.

C. flying in different directions.

An astronaut floating alone in outer space throws a baseball. If the ball moves away at 20 m/s, the astronaut will A. move in the opposite direction at a higher speed. B. move in the opposite direction at 20 m/s. C. move in the opposite direction at a lower speed. D. none of the above

C. move in the opposite direction at a lower speed.

The force on a dropped apple hitting the ground depends upon A. the speed of the apple just before it hits. B. whether or not the apple bounces. C. the time of contact with the ground. D. all of the above

D. all of the above

When Peter tosses an egg against a sagging sheet, the egg doesn't break due to A. reduced momentum. B. reduced impulse. C. both of these D. neither of these

D. neither of these

A 1-kg glider and a 2-kg glider both slide toward each other at 1 m/s on an air track. They collide and stick. The combined mass moves at A. 0 m/s. B. 1/6 m/s. C. 1/2 m/s. D. 1.5 m/s. E. 1/3 m/s.

E. 1/3 m/s.

The average braking force of a 1000-kg car moving at 10 m/s braking to a stop in 5 s is A. 5000 N. B. 1000 N. C. 4000 N. D. 3000 N. E. 2000 N.

E. 2000 N.