Week 1
Topic: Gravitation and Weightlessness
Introduction
Gravitational is a science concept that lead had been known and understood from Newton’s time. It was he who propounded the laws of universal gravitation from mathematical theory. Since that time, the theory has been used by other scientists in computing various constants and quantities that relate to objects on earth and in space
Meaning of Gravitation
There is a force which pulls things thrown upward towards the earth. This force is called gravitation.
The scientist discovered the existence of this force was Isaac Newton. He said that the force of gravity or gravitational force exists between all bodies. Thus, any two masses which are separated by a distance have a force of attraction called gravitation existing between them. Gravitational force is that force which pulls us towards the earth. It is this force that gives all objects their weight. The weight of an object is the force with which the earth pulls the object.
Weightlessness
When an object moves round a circle at high speed, a force called centripetal force acts on it. This force is one that makes a body moving with constant speed to remain in its circular motion. It is always directed towards the centre of the circle.
The total gravitational force on a body is composed of two forces for an object moving in a circle. The first component is its weight, while the other is the centripetal force. If the speed is very high, the centripetal force may be nearly equal to the weight. When this happens, the moving body experiences weightlessness.
Weightlessness is a condition that occurs in objects in fast circular motion when the centripetal force is equal to the weight of the object. In this condition, the two forces are equal and opposite
Effects of Gravitation on Objects
- Gravity causes objects to move e.g. a falling fruit from the top of a tree
- Gravity provides an objects revolving in a circular motion with centripetal force especially large objects in space such as the moon.
