Work and energy

What is the SI unit of work?

• 1 Joule
• 2 Newton
• 3 Pascal
• 4 Watt

How much work is done by a force of 20 N moving a body 5 m in its own direction?

• 1 15 J
• 2 25 J
• 3 100 J
• 4 4 J

What is the kinetic energy of a 2 kg body moving at 3 m/s?

• 1 6 J
• 2 12 J
• 3 9 J
• 4 18 J

What is the potential energy of a 5 kg mass at a height of 10 m? (g = 10 m/s²)

• 1 15 J
• 2 50 J
• 3 500 J
• 4 5 J

Power is defined as:

• 1 Energy x distance
• 2 Force x time
• 3 Work x time
• 4 Work / time

A machine does 600 J of work in 20 s. What is its power?

• 1 3 W
• 2 580 W
• 3 30 W
• 4 12000 W

Energy cannot be created or destroyed, only changed from one form to another. This is the law of:

• 1 Gravitation
• 2 Reflection
• 3 Conservation of energy
• 4 Inertia

A falling stone's potential energy changes mainly into:

• 1 Sound only
• 2 Light
• 3 Nuclear energy
• 4 Kinetic energy

1 kilowatt hour equals:

• 1 3600 J
• 2 3.6 x 10⁶ J
• 3 3.6 x 10³ J
• 4 1000 J

Which of these is a renewable source of energy?

• 1 Solar
• 2 Petrol
• 3 Natural gas
• 4 Coal