Chapter 15 - Energy & Work Done

One joule of work is done when

• one gram mass moves 1 metre

• one kilogram mass falls 1 metre

• force of one Newton is exerted over an area of 1 square metre

• force of one Newton moves an object through a distance of 1 metre

The unit used to measure work is the same as the unit used to measure

• energy

• force

• mass

• pressure

A climber, whose weight is 800 N, climbs a vertical distance of 50 m. The amount of work that he does is

• 40 J

• 400 J

• 4 kJ

• 40 kJ

Which of the following have chemical potential energy?

I. A chocolate bar

II. A litre of petrol

III. A piece of wood

• I and II only

• I and III only

• II and III only

• I, II and III

Which of these devices converts kinetic energy into electrical energy?

• Battery

• Dynamo

• Loudspeaker

• Motor

Which of these statements about energy and work done is true?

• Energy can be created if work is done.

• Energy can be destroyed if work is done.

• Work is always done when energy is used up.

• Energy can change from one form to another when work is done.

Which of the following changes in mass and speed would most likely result in the increase of the kinetic energy of an object?

• Mass increases; Speed increases

• Mass increases; Speed decreases

• Mass decreases; Speed increases

• Mass decreases; Speed decreases