sir,pleaze give me 05 example of  positive ,negative ,zero work done.

Hi Mishra!

Examples of positive work:

(1)  Pushing a book on a table to some distance

(2)  Lifting a bucket of water

(3)  Pulling a box on the floor to another place

(4)  Climbing a tree

(5)  Kicking a football

Examples of negative work:

(1)  The work done by the frictional force, when we push the book to a distance.

(2)  The work done by the gravitational force, when we are lifting a bucket of water from the well.

(3)  The work done by the gravitational force, when we are climbing on a tree.

(4)  The work done by the frictional force of air, when a ball is falling downwards.

(5)  The work done by the buoyant force, when a coin is sinking.

Examples of zero work:

(1)  If we push a wall, the wall remains unaltered. The work done by us on the wall is zero

(2)  If a person is walking horizontally with a load on his head, then the work done by the person against gravity is zero.

(3)  The work done against gravity in moving a book horizontally on a table is zero.

(4)  If we try to move a heavy box, and the box is not at all moving, then the work done by us will be zero.

(5)  The centripetal force acting on an object under circular motion does zero work on the object.

Cheers!!