In each of the following 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.
Step 1: Formula for work done
Work done on a body is given as,
W = (F cos θ) d
Where, is the work done by the force.
is the force, is the displacement caused due to the force
is the angle between the force and the displacement
Step 2: Determine work done for the first case
The direction of force acting on the block to the displacement.
Here .
Step 3: Determine work done in the second case
The direction of the force on the block is in the direction of displacement.
The angle between the force and displacement is .
Step 4: Determine work done in the third case
The direction of force on the block is opposite to the direction of displacement.
Here .
Hence, the work done in the first case is zero,
The work done in the second case is positive.
The work done in the third case is negative.