The sign of work done by a force on a body is important to understand. State carefully if the following quantities are poisitve 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 gravitational force in the above case. (c ) Work done by friction on a body sliding down an iniclined plane.
(d) Work done by an applied force 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.

Options

A. `B,D` and `E` only
B. `A` and `C` only
C. `B` and `D` only
D. `B` and `E` only

Answer

D