Question

A crane pulls up a car of mass $500kg$ to a vertical height of $4m$. So, work done by the crane is:

• A. $19.6J$
• B. $19.6kJ$
• C. $19600kJ$
• D. $4900J$

Answer 1

The correct option is B $19.6kJ$

To raise the car, the crane has to do work against the force of gravity.
Therefore, the force required to lift the car, $F=mg=500\times 9.8N=4900N$
Displacement, $S=$ vertical height raised $=4m$.
$\therefore$ Work done, $W=F.S=4900\times 4J=19600J=19.6kJ$