The sign of work done by a force on a body is important to understand. 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.

The sign of work done by a force on a body is important to understand. State carefully if the following quantities are positive or negative:
b) Work done by gravitational force when a man in lifting a bucket out of a well by means of a rope tied to the bucket.

The sign of work done by a force on a body is important to understand. State carefully if the following quantities are positive or negative:

(c) work done by friction on a body sliding down an inclined plane

The sign of work done by a force on a body is important to understand. State carefully if the following quantities are positive or negative:

(d) work done by an applied force on a body moving on a rough horizontal plane with uniform velocity

The sign of work done by a force on a body is important to understand. State carefully if the following quantities are positive or negative,

(e) Work done by the resistive force of air on a vibrating pendulum in bringing it to rest.