L-04 Uniform circular motion / Magnitude of centripetal force

Uniform circular motion / Magnitude of centripetal force :

• An object moving in a circle with constant speed, when the object is constantly acted upon by a force directed towards the centre of the circle. This force is called the centripetal force.

The speed of the planet can be expressed in terms of the period of revolution T as follows.

Newton concluded that Centripetal force is 

• The force acting on the planet and is responsible for its circular motion. 
• It must be inversely proportional to the square of the distance between the planet and the Sun. 
• Newton identified this force with the force of gravity.
• He postulated the inverse square law of gravitation. 
• The gravitational force is much weaker than other forces in nature.
• It controls the Universe and decides its future. 

Do you know ? 

1. High and low tides occur at different times at different places. 
2. The level of water in the sea changes because of the gravitational force exerted by the moon. 
3. Water directly under the moon gets pulled towards the moon and the level of water there goes up causing high tide at that place. 
4. At two places on the earth at 90° from the place of high tide, the level of water is minimum and low tides occur there.