IB Physics - Work, Power, Energy

Each of the boxes shown is pulled for 10 m across a level, frictionless floor by the force given. Which box experiences the greatest change in its kinetic energy?

• A

• B

• C

• D

• E

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

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

Calculate the PE of a 2 kg cat perched 10 meters above the ground. 

• 20 J
• 200 J
• 2.04 J
• 200 W

A 10.0 kg box is accelerated from 2.0 m/s to 4.0 m/s.  What is the amount of work in joules needed to accelerate the box?

• 50.0
• 60.0
• 20.0
• 45.0

As a pendulum swings from its highest to lowest position, what happens to its kinetic and potential energy? 

• Both the potential energy and kinetic energy decrease
• The potential energy decreases while the kinetic energy increases 
• The kinetic energy decreases while the potential energy increases 
• Bothe the potential energy and kinetic energy increase 

Where is the car moving fastest?

• A

• B

• C

• D

The % energy efficiency of an appliance is

• total energy input/ useful energy output x 100

• useful energy output /total energy input x100

• total energy input x useful energy input x100

• useful energy output /total energy input x50