Question

The work done by a force on a body will be positive if the body:

• A. does not move
• B. moves perpendicular to the direction of applied force
• C. moves along the direction of applied force
• D. moves opposite to the direction of applied force

Answer 1

Answer: (C)

Work-done by a force on a body $=F\times s$
$F=$ Force acting on the body
$S=$Displacement due to the force applied

Work done will be positive if the direction of force and displacement are the same.
Work done is zero when force and displacement is perpendicular.
When an object does not move then $s$ will be 0, so W $=0$
When object moving opposite to the direction of applied force then work done is negative.