Physics Chapter 6 Study Guide

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 (1) + 2(-1) = 1 + 2 (v) 1 + -2 = 3v -1/3 = v

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

1 unit

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

1(1) + 5(0) 1 + 0 *1 kg 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(1) + 5(0) = 1 + 5 (v) 1 + 0 = 6v *1/6 = v*

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

1/2 = *.5*

A 10 kg cement block moving horizontally at 6 m/s plows into a bank of sand and comes to a stop in 2 seconds. What is the average impact force on the bank?

10(6)/2 = *30 N*

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

1000 (10) / 5 2000

A motorcycle of mass 100 kilograms slowly rills 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

1000*3*10 3000 kg m/s

The speed of a 4-kg ball with a momentum of 12 kgm/s is

12 = 4(V) 3 = v

A 2 kg rifle that is suspended by strings fires a 0.01 kg bullet at 200 m/s. The recoil velocity of the rifle is about

2 (V) = 0.01 (200) 2v = 2 *v = 1*

A 40 kg football player leaps through the air to collide with and tackle a 50 kg player heading toward him also in the air. If the 40 -kg player is heading to the right at 9 m/s and the 50 kg player is heading toward the left at 2m/s. What is the speed and direction of the tangled players?

40(9) + 50(2) = 90V 360 + 100 = 90v *2.9 = v* *2.9 to the -->*

The mass of a ball moving at 3 m/s with a momentum of 48 kg m/s is

48 = 3(M) 16 = M

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

5(1) + 1(0) = 5 + 1 (v) 5 + 0 = 6v *5/6 = V*

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 (-1) + 5000 (2) = 5000 + 5000 (v) -5000 + 10,000 = 10,000v 5000 = 10000v *v = 5000*

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

5000 (2) + 10,000 (0) = 5000 + 10,000 (v) 10,000 + 0 = 15,000v 10,000 = 15,000v *2/3 m/s*

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

5000(v) + 10,000 (0) = 5000 + 10,000 (2) 5000v + 0 = 30,000 *v = 6 m/s*

An 8 - kg blob of clay moving horizontally at 2 m.s hits a 3 kg blob of clay at rest. What is the speed of the two blobs stuck together immediately after the collision?

8(2) + 3(0) = 11 (v) 16 = 11v 1.45 m/s = V

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

a pickup truck speeding along a highway

Two vehicles with equal magnitudes of momentum traveling at right angles to each other undergo an inelastic collision. The combined wreck moves in a direction

at 45 degrees to the direction of either car before collision

A firecracker bursts while freely falling. The combined momentum of its fragments

equals the momentum of the firecracker at the time of burst

The force that accelerates a rocket in outer space is exerted on the rocket by the

exhaust gases

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 with the force that stops the car, the force needed to stop the truck is

greater

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

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

greater with the haystack greater with the brick wall *both the same*

A softer landing occurs when a falling object bounces from a surface

in an extended time

When a boxer moves into an oncoming punch, the force experienced is

increased

Padded dashboards in cars are safer to an accident that non-padded ones because passengers hitting the dashboard encounter

lengthened time of contact

A large heavy truck and a small baby carriage roll down a hill. Neglecting friction at the bottom of the hill, the baby carriage will likely have

less momentum

If you can't avoid being hit by a fast moving object, you'll suffer contact force if you can extend that force over a

longer time

A car traveling along the highway breaks to a stop over a certain distance. More braking force is required if the car has

more mass more momentum less stopping distance *all of the above*

If a monkey floating in outer space throw 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 red car has a head-on collision with an approaching blue car with the same magnitude of momentum. A green car driving with the same momentum as the other cars collides with an enormously massive wall. Which of the three cars will experience the greatest impulse?

red car blue car green car *all 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

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

the bag your car *both the same*

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

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

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

5(1) + 1(4) = 5 + 1 (v) 5 + -4 = 6v 1 = 6v *1/6= v*

A 5-kg blob of blob moving horizontally at 4 m/s has a head-on collision with a 4 kg blob of clay that moves toward it at 2 m/s. What is the speed of the two blobs stuck together immediately after the collision?

5(2) + 4(2) = 5 + 4 (v) 20 + 8 + 9v 3.1 m/s

Which has the greater momentum?

a container ship a bullet *either of these depending on speed*

Is it correct to say that impulse is equal to

a corresponding change in momentum

When you jump from an elevated position you usually bend your knees upon reaching the ground, which makes the time of he 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

A cannon recoils while firing a cannonball. The speed of the cannon's recoil is relatively small because the

cannon has much more mass than the cannonball

When Freddy Frog drops vertically from a tree onto a horizontally-moving skateboard, the speed of the skateboard

decreases