Forces: Work done and energy transfers.

Question 1

What is work done?

Answer 1

• When a force is used to move an object, energy is transferred.

Question 2

How do we calculate work done?

Answer 2

• Work done (J)= Force (N) x Distance (m).
• Distance must be in the line of action of the force.
• Unit is also: netwon-meter.
• 1 newton meter of work= 1 joule.

Question 3

What happens when the car brakes?

Answer 3

• When the brake is pressed:
• Force of friction acts between the brake and the wheel.
• Kinetic energy store of the car is transferred to the thermal energy store of the brakes.
• Temperature of the brakes increases and at the same time the car slows down and looses its kinetic energy.
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