Question

When does a body rotate? State one way to change the direction of rotation of the body. Give a suitable example

Answer 1

Hint: If every particle in the body moves around a single line in a circle, pure rotational motion occurs. This line is called the rotation axis. Then the radius vectors from the axis to all of the particles simultaneously undergo the same angular displacement. The rotation axis does not need to go through the body.

Complete answer:
1.When there is a net torque acting upon it, a body rotates. We will have to provide a retarding torque to change the direction of rotation of a rotating body with a fixed axis that will eventually stop the rotation and start in the opposite direction.
2. As a consequence, the body's direction of rotation will change. But if the axis is not fixed, by simply reversing the axis of rotation, the direction of rotation can be reversed.
3.Due to torque, the body rotates and the direction of rotation can be altered if we apply retarded torque or alter the direction of torque. A body will remain in its state of rest or movement, as per Newton's first law, until or unless an external force is applied to the body.
4. The direction of both angular velocity and angular momentum is defined using the right hand rule as the direction in which the thumb of your right hand points when you curl your fingers in the rotation direction.
5. Example: The force applied to the body at a suitable point rotates the body around the axis, passing through the pivot point, when the body is pivoted at a point. By changing the point of application of force, the direction of rotation can be changed.

Note:
Due to torque, the body rotates and the direction of rotation can be altered if we apply retarded torque or alter the direction of torque. A body will remain in its state of rest or movement, as per Newton's first law, until or unless an external force is applied to the body. The angular velocity direction and the angular momentum direction are perpendicular to the rotation plane.