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# HC Verma for Class 11 Physics Chapter 7:Circular Motion

Chapter 7, Circular Motion, deals with circular motion. The formula V = 2πr/t helps determine an object's velocity with respect to another object in a linear motion. Similarly, circular motion comes into play in the case of a circular path.

Circular motion can be defined as the rotational movement of an object along a circular path. The angular rate of rotation and speed remain constant during uniform circular motion. However, during non-uniform circular motion, the rate of rotation does not remain constant. Some common examples of circular motion include man-made satellites which revolve around planet Earth, rotating ceiling fans, moving wheels of cars, windmill blades and gas turbine gears.

An important aspect of circular motion is that the direction of motion changes continuously. Hence, circular motion ought to be described in terms of angular variables. Angular displacement is defined as the angle turned by a rotating particle per unit of time. It is represented by ∆θ and is measured in radians.

The rate of change in the angular displacement of a particle moving in a circular path is called Angular velocity. The chapter further discusses centripetal force. A particle moving in circular motion is always directed towards the centre, and v 2 /r gives its acceleration. On applying Newton's second law of motion, the formula:

Fcen=mv2/r  Here, Fcen is the centripetal force that directs the particle in a circular motion towards the centre. The force of gravity, friction and the tension observed in a string are some examples of centripetal forces.