phys 107 test 2 test

Two billiard balls of the same mass roll straight toward each other. The first has a velocity of +5 m/s and the second has a velocity of -3 m/s. After colliding, the first ball has a velocity of

-3 m/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 on a frictionless surface. The speed of the putty thereafter is

1/6 m/s.

A longer cannon barrel is advantageous because it increases

A impulse delivered to the ball by allowing the force to be applied for a longer time. C the ballʹs momentum by increasing its velocity

How can you increase the angular momentum of a ball spinning on a string?

A increase the length of the string B spin the ball faster

Acrobat Bart at the circus drops vertically onto the end of a see -saw, with his partner Art equidistant from the fulcrum at the other end. Art is propelled straight upward a distance twice that of Bartʹs dropping distance. Neglecting inefficiencies we see

Art has half the mass of Bart.

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 have a greater

NONE A speed. B acceleration. C momentum.

Which jar will roll down an incline in the shortest time, an empty one or one filled with peanut butter?

The filled jar

The famous Leaning Tower of Pisa doesn't topple over because its center of gravity is

above a place of support.

A hydraulic press, like a wheel and axle, is capable of multiplying force input.

always true

In class, I laid on a bed of nails with cinder blocks stacked on top of me. When Thomas struck the blocks with the sledgehammer, the kinetic energy of the hammer went into

cinder block??

When a twirling ice skater brings her arms inward, her rotational inertia

decreases.

A car travels in a circle with constant speed. The net force on the car is

directed towards the center of the curve.

Two pool balls, each moving at 2 m/s, roll toward each other and collide. Suppose after bouncing apart, each moves at 4 m/s. This collision violates conservation of

energy

When a car is braked to a stop, its kinetic energy is transformed to

heat.

An upright broom is easier to balance when the heavier end is

highest, farthest from your hand.

A heavy truck and a light truck roll down a hill. Neglecting friction, at the bottom of the hill, the heavy truck will have greater

kinetic energy.

If you do twice the usual work on an object in half the usual time, your power output is

quadruple the usual power output.

Your pet hamster sits on a spinning record player. If the angular speed of the record player doubles and he moves to a point half as far from the center, then his linear speed

remains the same.

Centrifugal forces are an apparent reality to observers in a reference frame that is

rotating.

The center of mass of a human body is located at a point

that changes as a person bends over.

Which has greater kinetic energy, a car traveling at 30 km/hr or a car of half the mass traveling at 60 km/hr?

the 60 km/hr car

When trying to turn a stubborn screw, you can generate twice as much torque by switching to a screwdriver with a handle that is

twice as wide

How much work is done on a crate as it slides 10 m across the floor at a constant velocity of 2 m/s?

0 J

Two 1 kg billiard balls roll toward each other, each moving with speed 10 m/s. What is the combined momentum of the two balls?

0 kg m/s

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

1 m/s.

A car moving at 50 km/hr skids 20 m with locked brakes. How far will the car skid with locked brakes if it were traveling at 150 km/hr?

180 m

Suppose the circumference of a bicycle wheel is 2 meters. If it rotates at 1 revolution per second when you are riding the bicycle, then your speed will be

2 m/s.

If you need to tighten a bolt with 80 Nm of torque using a wrench with a handle that is 25 cm from the axis of the bolt, how much force do you need to apply when turning the wrench?

320 N

A jack system will increase the potential energy of a heavy load by 400 J and generate 600 J of heat with a work input of 1000 J. The efficiency of the jack system is

40%.

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?

80 J

To do 10 J of work pushing a crate using 2 N of force, you will need to push the crate

5 m.

How long will it take to stop a 1500 kg car moving at 20 m/s with a braking force of 6000 N?

5 s

A woman alleviates her back pain in the fifth month of pregnancy by wearing a backpack instead of carrying a purse. When the pain resurfaces in the ninth month of pregnancy, she can reduce the back pain once again by

A walking in snowshoes. B adding a few books to her backpack. C hanging the backpack from the end of a stick carried over her shoulder. D delivering the baby.