Energy, Work, Power & Simple Machines

Energy is

• a push or a pull

• the ability to do work

• a force like gravity or friction

• none of the above

Energy can

• be converted from one form to another

• allow work to be done

• be potential or kinetic

• all of the above

• none of the above

At which position does the pendulum possess 100% kinetic energy?

• A

• B

• C

• D

• E

At which positions does the pendulum possess 100% potential energy?

• A & B

• B & C

• C & D

• D & E

• A & E

What can be said about the energy possessed by the pendulum at positions B and D?

• The pendulum has neither potential nor kinetic energy at those positions.

• The pendulum has 75% PE at B and 25% KE at D.

• The pendulum has 50% PE and 50% KE at both B and D.

• The pendulum has 25% PE at B and 75% KE at D.

The formula for calculating PE is PE = mgh where

m = mass; g = gravitational acceleration; h = height.

Which factor in the formula is always constant?

• mass

• gravitational acceleration

• height

The formula for calculating an object's KE is KE =  $\frac{1}{2}mv^2$ 

Two bowling balls of different masses are rolling down the bowling lane at the same velocity.

What is true about their respective kinetic energies? 

• The ball with the greater mass will have a lower KE.

• The ball with the greater mass will have a greater KE.

• Their KEs will be the same.

• There is not enough information given to determine that.

The blue, purple, and blue balls in this diagram have equal masses.

Which has the lowest PE and why?

• The green one because it is furthest to the left.

• The purple one because its height is the lowest.

• The blue one because it is being held by the "person".

This diagram illustrates how a power plant transforms the energy in coal into another form of energy that can power many other devices.

The energy in coal is in the form of

• chemical potential energy

• elastic potential energy

• mechanical kinetic energy

• sound kinetic energy

What type of energy is the energy in coal converted to when it leaves the power station?

• heat

• kinetic

• electrical