How much work is done by a weight lifter when he holds a weight of $80 \,kg$ on his shoulders for two minutes?

When do we say that work is done?

$A$ mass of $10\, kg$ is at a point $A$ on a table. It is moved to a point $B$. If the line joining $A$ and $B$ is horizontal,what is the work done on the object by the gravitational force? Explain your answer.

Justify giving proper reasoning whether the work done in the following case is positive or negative: Work done by a man in lifting a bucket out of a well by means of a rope tied to the bucket.

In each of the following cases,a force,$F$ is acting on an object of mass,$m$. The direction of displacement is from west to east,shown by the longer arrow. Observe the diagrams carefully and state whether the work done by the force is negative,positive,or zero.

Define $1\, J$ of work.