Physics Concepts for JEE 2016: Work and Power in Rotational Motion
In dynamics we have studied that work is the amount of energy which is transferred in the process of displacement of a body by external force acting on it. The amount of work is calculated by the product of force magnitude and the displacement from the point of application of force in the direction of force.
Similarly we can calculate the work done by
external torques on a body in rotational motion. This can be calculated by the
product of torque magnitude and the angular displacement of the body in the
direction of torque vector. Hence, work done in rotational motion can be
positive or negative i.e. it can increase or decrease the kinetic energy of the
body.
To understand the basics of work in
rotational motion see the video below –
The work-energy theorem is also applicable
here for the amount of work done on or by the body in rotational motion which
increases or decreases its kinetic energy. The time rate of work done on a body
in rotational motion is the power which can be given by the dot product of the
torque and angular velocity of body in rotation.
To understand applications of work and
power in rotational motion see the example videos below –