# WORK, ENERGY AND POWER

Energy is used up when work is done. The energy stored up in our muscular system is made available when we are to do work. The stored-up energy (potential energy) is converted to kinetic energy as work is being done.

## MEANING OF WORK, ENERGY AND POWER

### Work

Work is done whenever a force is applied to cause a body to move. For instance when you lift a bucket from the ground to your head and stand at a point for several hours ; you have only done work by lifting the bucket of water from the ground  to your head ,you have done no work in carrying the bucket of water as long as you remain on the spot.

### Energy

Energy is the ability to work by exerting a force to move an object through a distance. Anything that is capable of doing work has energy. For instance,a boy running a race of 100 meter has energy because he is able to move some distance. Work and energy are measured in the same unit as the JOULE.

### Power

Power is defined as the time rate of doing work. If two boys   of the same weight are to climb a flight of stairs of the same height, the boy that gets to the top first is said to have the greater power. This is because he has done the work of moving his weight through that height at a shorter time.

Hence, in mathematical terms, power is expressed as: power = workdone or energy expended/time taken. If the workdone is in joules and the time is in seconds, then the power is watts.

1 watt=1 joule per second

Power can also be commonly expressed in kilowatts (KW), megawatt (MW) and horse power (h.p)

1 KW=1,000W

1MW=1,00 0,000W

1 h.p=746W

## EVALUATION

1. Which of the following is not a source of energy? A. Coke b. Coal c. Smoke       d .Water
2. ————- is done when a force moves some things through distance.
3. Work b. Energy c. Movement d. Effort
4. The energy obtained is cassava is ———————-
5. Mechanical b. Chemical  c. Heat   d. Power
6. A body which exerts force has ——————–
7. Strenght b. pressure c. Energy   d. Power
8. The light energy from the sun is called————–

6.The unit of energy is—————————–

SECTION B

1.Define the following

1. Work ii Energy iii. Power

2.Give the unit of measurement of the following.

1. Work ii Energy iii Power

SKILL ACQUISITION

Electrical Energy

Magnetism

SOUND ENERGY

LIGHT ENERGY