PHYS 101 Test 2

Two freight trains of equal mass roll toward each other with the same speed. What is the combined momentum of the two trains?

0 kg m/s

A 1 kg chunk of putty moving at 1 m/s collides 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 40% efficient machine is required to do 400 Joules of work during a cycle. How much energy does it consume during each cycle?

1000j

The 6 kg bowling ball is initially at rest 2 meters above its lowest point What is the potential energy of the ball at its highest point?

120j

The 6 kg bowling ball is initially at rest 2 meters above its lowest point. What is the kinetic energy of the ball at the bottom of its arc?

120j

Some old physics prof pulls a cart across the room a distance of 5 meters. Afterward the cart has 70 Joules of kinetic energy. What force did he exert during the pull?

14 newtons

A 3 kg ball has a momentum of 48 kg m/s. What is the ball's speed?

16 m/s

A satellite in orbit at a distance of one earth radius has an apparent weight in that orbit of 500 N. When it lands on the earth, the force of gravity on the satellite is

2000N

If you add 350 Joules worth of gasoline to your car and get only 87.5 joules of kinetic energy out of it. What is its efficiency?

25%

A 70 kg bungee jumper jumps from a height of 40 m. How much potential energy does she have just before jumping?

28,000j

An asteroid exerts a 360 N force on a nearby spacecraft. If the spacecraft moves to a point 3 times as far from the center of the asteroid, the force will be

40N

A 30 kg boy sits at a distance of 2 m from the center of a see-saw. What mass is his sister if she sits at the 1.5 meter mark to balance him?

40kg

How much time would it take a 60 Watt light bulb to consume 300 Joules of energy?

5 seconds

A 5 kg fish swimming at a velocity of 1 m/s swallows an unsuspecting 1kg fish initially at rest. The speed of the larger fish after his lunch is

5/6 m/s

The 6 kg bowling ball is initially at rest 2 meters above its lowest point. How fast is the ball moving at the bottom of its arc?

6.3m/s

The 6 kg bowling ball is initially at rest 2 meters above its lowest point. What is the kinetic energy halfway down?

60j

Traveling at 10 mi/hr in a school zone requires 20 feet to stop your car. If you are traveling at 20 mi/hr, what distance would you need to stop?

80ft

My sister at a height of 25 m has a potential energy of 22,500 Joules. What is her mass?

90kg

An object that has gravitational potential energy must be

At an elevated position

A freight train rolls along a track with considerable momentum. If it rolls at the same speed, but has half as much mass, its momentum is

Halved

The 6 kg bowling ball is initially at rest 2 meters above its lowest point. Which is greater, the potential energy at 1m or the kinetic energy at 2 m?

PE at 1m

I lift my 40 kg son to a height of 1 meter, while he lifts me (80 kg) to a height of 0.5 m. My son did _______as I did.

The same work

A coin and a ring of the same mass and diameter roll down an incline starting at the same time. The one to reach the bottom first will be the

coin

A pizza chef tosses pizza dough in the air so that it spins. As it spins, its diameter slowly gets bigger. As this happens, its rotational speed ________.

decrease

I spin my son on the merry-go-round at the playground. When he walks inward towards the center of the merry-go-round, the rotational inertia of the system will_____.

decrease

If all of the inhabitants of the earth would climb to the top of a ladder, the angular speed of the earth would

decrease

If the Earth expanded to twice its diameter with the same mass, its rotational speed would

decrease

If the radius of the earth somehow increased with no change in mass, your weight would

decreases

The centripetal force acting on an object in constant angular motion works to change its

directional motion

According to Newton the greater the distance between interacting objects, the

less the gravitational force between them by the square of the distance

Two objects rotate on a merry-go-round, one at r=1 m and the other at r=2m from the center. The object rotating at 1 m has less _______than the object at 2 m.

linear velocity

Which has a greater kinetic energy, a 5 kg mass traveling at 30 m/s or a 2.5 kg mass traveling at 60m/s?

the 2.5 kg mass

It is correct to say that impulse is equal to

the change in momentum