More Work, Power & Energy

The faster an object moves, the ________ kinetic energy it has. 

• more
• less
• none of the above
• all of the above 

Gravitational potential energy depends on the ________ and ________ of the object. 

• Height and mass
• Friction and movement
• Mass and Movement
• Height and Friction 

What is the formula for calculating the total amount of mechanical energy?

• ME = KE + PE
• KE = ME + PE
• PE = KE + ME
• ME = 1/2 mv²

If a system is isolated, the total energy of the system

• Increases constantly.

• Decreases constantly.

• Is constant.

• Depends on the work done on the system.

• Depends on the work done by the system.

Rank in order, from largest to smallest, the gravitational potential energies of the balls.

• 1 > 2 = 4 > 3

• 1 > 2 > 3 > 4

• 3 > 2 = 4 > 1

• 3 > 2 > 4 > 1

Starting from rest, a marble first rolls down a steeper hill, then down a less steep hill of the same height. Ignoring friction, for which is it going faster at the bottom?

• Faster at the bottom of the steeper hill

• Faster at the bottom of the less steep hill

• Same speed at the bottom of both hills

• Can’t say without knowing the mass of the marble

A small child slides down the four frictionless slides A–D. Rank in order, from largest to smallest, her speeds at the bottom.

• vD > vA > vB > vC

• vD > vA = vB > vC

• vC > vA > vB > vD

• vA = vB = vC = vD

Four students run up the stairs in the time shown. Which student has the largest power output?

• A

• B

• C

• D

You are traveling along a freeway at 65 mi/h; your car has kinetic energy. You suddenly skid to a stop because of congested traffic. What happened to the kinetic energy your car just had?

• It is all in internal energy in the road

• It is all in internal energy in the tires

• Some of it has transformed to internal energy for the tires and the road, and some of it transferred away by sound energy and thermal energy into the air.

• It was destroyed

Which requires more power – a person walking up stairs or a person running up stairs?

• walking

• running

• they require equal power output

• no power is required at all