# GRAVITATION AND WEIGHTLESSNESS

## MEANING OF GRAVITATION

Gravitation is a force that has effect on the stability of a body. If an object is tossed up the air, it will fall back to the ground because the earth exerts an attraction on it. This attraction is called gravitational attraction.

The gravitational attraction / force between any two object increases as the two objects approach each other.The earth has a great gravitational pull because it has a great mass. The gravitation pull of the earth is always directed to the centre.

## WEIGHTLESSNESS

Weightlessness is a feeling of being weightless. It does not mean having no weight. As someone move away from the surface, it progressively reduces. In the outer surface of the earth, a person or body has no weight because the gravitational pull of the earth is no longer acting there.

### EVALUATION

1. What is gravitation?
2. Define the term weightlessness.

## EFFECT OF GRAVITATION ON OBJECTS

1. Stability on Earth: Gravitation help every object in the earth include man to remain stable.
2. Weight: The weight of an individual is a measure of the gravitational pull of the earth on that person.
3. Revolution of the Moon round the Earth: Moon is able to revolve round the earth because the gravitational pull of the earth attracts it.
4. Balance of Planets in our Solar System: The sun and all the planets in our solar system exercise gravitational pulls on one another and mutually balance on another in space.
5. Work is done against gravity in lifting an object form the Earth: Lifting an object from the ground involves opposing gravitational pull, therefore work is done against gravitational attraction of the earth.

### EVALUATION

1. Define gravitational pull.
2. State four effects of the gravitational pull.

## GENERAL EVALUATION

1. What is gravitation?
2. Define weightlessness.
3. Define gravitational pull.
4. State four effects of the gravitational pull.
5. Describe the effect of gravitation on stone, a feather and a book.

## WEEKEND ASSIGNMENT

1. When a metal ball of 20kg and a wooden ball of 10kg are dropped from the some height A. the metal ball reach the ground before wooden ball B. both balls will reach the ground at the same time C. the wooden ball falls faster than metal ball D. the metal ball null full sideways.
2. Gravitational force is a force of ____ A. separation B. attraction C. friction
3. opposition.
4. The earth has a large gravitational pull on object because the earth A. has plants and animals B. is a planet C. is large in size  revolves.
5. The earths gravitational pull on an object is represented by that objects A. weight
6. size C. volume D. materials.
7. The ability of an object to remain stable on earth is due to ____ A. gravitational pull B. weightlessness C. moon and earth sizes D.  its height.

## THEORY

1. Describe the effect of gravitation on stone, a feather and a book.
2. Where does object become weightless and why?

SPACE TRAVEL

CALCULATION OF GRAVITATIONAL FORCES

FORCES

ENVIRONMENTAL POLLUTION

ENVIRONMENTAL POLLUTION