physics exam 1 chapter 6

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

0.5 m/s.

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 piece of putty moving with 1 unit of momentum strikes and sticks to a heavy bowling ball that is initially at rest. Both move with a combined momentum of

1 unit.

As Bronco Brown steps off a hovering high-flying helicopter and falls through the air, he experiences

1. an impulse. 2. a decreasing acceleration. 3. an increasing speed.

When a vertically falling firecracker bursts, the vector sum of momentum fragments

1. in the vertical direction equals the momentum of the firecracker before bursting. 2. in the horizontal direction cancels to zero.

You're driving down the highway and a bug spatters into your windshield. Which undergoes the greater change in momentum during the time of contact?

1. your car 2. the bug

Two identical gliders slide toward each other on an air track. One moves at 1 m/s and the other at 2 m/s. They collide, stick, and moves at

1/2 m/s.

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

1/3 m/s.

The impulse-momentum relationship is a direct result of

Newton's 2nd law.

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

a pickup truck speeding along a highway

The total momentum of a flock of identical birds could be zero only if the birds are

flying in different directions

Freddy Frog drops vertically from a tree onto a horizontally-moving skateboard. The reason he doesn't slip off the skateboard is due to

friction between his feet and the board.

If a monkey floating in outer space throws his hat away, the hat and the monkey will both

move away from each other, but at different speeds.

An astronaut floating alone in outer space throws a baseball. If the ball moves away at 20 m/s, the astronaut will

move in the opposite direction at a lower speed.

A falling 1-N apple hits the ground with a force of about

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A sandbag motionless in outer space is hit by a three-times-as massive sandbag moving at 12 m/s. They stick together and move at a speed of

none of the above

Compared with 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.

A 5-kg fish swimming at 1 m/s swallows an absent-minded 1-kg fish at rest. The speed of the larger fish after lunch is

5/6 m/s.

Two 5000-kg rail 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, and roll together with a combined momentum of

5000 kg m/s.

The change in momentum that occurs when a 1.0 kg ball traveling at 4.0 m/s strikes a wall and bounces back at 2.0 m/s is

6 kg m/s.

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

6 m/s

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

1/6 m/s.

Consider massive gliders that slide friction-free along a horizontal air track. Glider A has a mass of 1 kg, a speed of 1 m/s, and collides with Glider B that has a mass of 5 kg and is at rest. If they stick upon collision, their speed after collision will be

1/6 m/s.

A 5000-kg freight car moving at 2 m/s collides with a 10,000-kg freight car at rest. They couple upon collision and move away at

2/3 m/s.

The average braking force of a 1000-kg car moving at 10 m/s braking to a stop in 5 s is

2000 N.

A motorcycle of mass 100 kilograms slowly rolls off the edge of a cliff and falls for three seconds before reaching the bottom of a gully. Its momentum upon hitting the ground is approximately

3,000 kg m/s.

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

about 1/10 as great.

If several balls are thrown straight up with different initial speeds, the quantity that will have the same value along their paths is their

acceleration.

Whether a truck comes to a stop by crashing into a haystack or a brick wall, the impulse is

both the same

The greater efficiency achieved with the curved blades of a Pelton wheel is due to

bouncing.

A cannonball following a parabolic path explodes into fragments. The momentum of the fragments

continue along the path as if the explosion didn't occur.

When bullets are fired from an airplane in the forward direction, the momentum of the airplane is

decreased.

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

decreases.

two vehicles with equal magnitudes of momentum traveling at right angles to each other undergo an inelastic collision. The magnitude of momentum for the combined wreck is

greater than the magnitude of momentum of either car before collision.

Whether a truck comes to a stop by crashing into a haystack or a brick wall, the stopping force is

greater with the brick wall.

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

longer time of contact.

It is correct to say that the impulse imparted to an object is equal to

the object's momentum change

A tiny gun made of a strong but very light material fires a bullet more massive than the gun itself. For such a weapon

the target would be safer than the shooter.

When a boxer is moving away from a punch, the force experienced is reduced because

the time of contact is increased.

To catch a fast-moving ball, you extend your hand forward before contact with the ball and let it ride backward in the direction of the ball's motion. Doing this reduces the force of contact on your hand principally because the

time of contact is increased.

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

zero