1. Produced by Tsang Siu Chung
WORK DONE & ENERGY
Produced by
Tsang Siu Chung

2. Work done work is done whenever a force moves an object.
In everyday language,work may mean anything that people do.
In science,it is given a more precise meaning:
work is done whenever a force moves an object.

3. Work = forcedistance moved in the
direction of the force
W = F s

4. W = F s W = F s cos  Joule ( J ) F F F F s s
Work is measured by newton metre (N m)
Joule ( J )

5. Important definition
1 joule of work is done when a force of 1 newton moves a distance of 1 metre in the direction of the force.

6. Energy ,like work, is measured in joule(J).
Things have energy if they can do work.We can think of energy as a capacity for doing work in the future.
Energy ,like work, is measured in joule(J).
BOB!

7. Now,we will talking about the mechanical energy.
The followings are different forms of mechanical energy.
Kinetic energy
Gravitational potential energy
Strain energy

8. Kinetic energy A moving object has kinetic energy.
The faster it moves the more energy it possesses.
When a human run,chemical energy from the food changed into kinetic energy.

9. Gravitational potential energy
When you lift a box up , it gains gravitational potential energy.
The higher the box the more gravitational potential energy it possesses.
If the box falls down , its gravitational energy is changed into kinetic energy.
BOX
Gain
gravitational
energy
BOX

10. Strain energy Another form of potential energy.
It is energy possessed by an elastic object when it is stretched , compressed or bent.
If the elastic is released , its strain energy is changed into the kinetic energy.

11. Work done = Energy transferred
Energy change and work
Work is done whenever energy is transferred from one from to another.
Work done = Energy transferred
Example:
If a falling stone loses 10 joules of gravitation
potential energy and gains 10 joules of kinetic
energy , the gravitational force acting does 10
joules of work in accelerating the stone.

12. Energy in one form
Energy in another form
Work is done

13. THE END “Work done & Energy”
This is the end of my project . I hope that you will have a general idea about Thank you.
THE END