Circular Motion and Gravitation
Circular motion and Gravitation
Circular motion is an interesting topic. It reminds us of our childhood game in which we attached a stone and rotated it above our heads. When we first started to learn about the solar system, we were taught that planets revolve around the sun in a circular orbit. Similarly, the moon revolves around the earth.
In this unit, we will learn about the circular motion of objects on earth in a general setting such as vertical circular motion and circular motion due to gravitation ( not considering elliptical orbit).
Angular Displacement
In case of rotational motion instead of calculating linear displacement we calculate angular displacement. Angular displacement is defined as the angle subtended by the object at the centre of the circle due to change in it's position. It's is measured in radians
Angular speed
We can easily understand the angular speed by relating it with linear speed.
In this case, just change linear distance by angular distance and divide by time.
Angular speed is equal to angular displacement per unit time.
Unit of angular displacement is radians per second (rad/s)
Time period
Time period is the time taken by an object to complete one round. It is also known as period. Time period of object is denoted by T.
Frequency is the number of rounds completed by object in one second.
Unit of frequency is Hz.
f= 1/T
Centripetal force
The motion of an object on circular path is called circular motion. According to Newton's first law, any object cannot change its position, direction or the speed without an external force. To change the direction of the object an external force is necessary so when an object moves in a circular motion there must be some external force. This type of force which keeps the object in its orbit is called as the centripetal force.
For example, when planets revolve around the sun a centripetal force is provided by gravitational force between the planet and the sun. In absence of gravitational force, the planet will drift away from its orbit and the sun.
Same concept works between the earth and artificial satellites. Artificial satellites are continuously accelerating towards the earth and they are in a state of free fall. This phenomenon of free fall is responsible for the weightlessness of astronauts in the international space station (ISS).
CONTACT
US
Tel. 123-456-7890
Fax. 123-456-7890
500 Terry Francois Street,
San Francisco, CA 94158
VISIT
US
Monday - Friday 11:00 - 18:30
Saturday 11:00 - 17:00
Sunday 12:30 - 16:30