Work done

The sign of work done by a force is important to understant. State carefully if the following quantities are positive or negative. (a) Work done by a man in lifting a bucket out of a well by means of a rope tied to the bucket. (b) Work done by the gravitational force in the above case. (c ) Work done by friction on a body sliding down an inclined plane. (d) Work done by an applied froce on a body moving on a rough horizontal plane with uniform velocity. (e ) Work done by the resistive force of air on a vibrating pendulum in bringing it to rest.

Assertion , No work is done if the displacement is zero Reason: Work done by the force is defined to be the product of component of the force in the the direction of the displacement and the magnitude of displacement.

STATEMENT-1: Work-energy theorem is consequence of Newton's laws of motion. STATEMENT-2: The work done by a conservative force along a closed path is zero. STATEMENT3: Work done by a constant force is independent of the path.

if work is done by the system then W is

A body is moved in a direction opposite to the direction of force acting on it.State whether the work is done by the work in done against the force.