Question

A force of $1000N$ was applied to stop a car that was initially moving with a constant velocity. The car stopped after moving through $10m$. How much is the magnitude of work done by the force?

• A. $1\times {10}^{4}J$
• B. $2\times {10}^{4}J$
• C. $3\times {10}^{4}J$
• D. $4\times {10}^{4}J$

Answer 1

The correct option is A $1\times {10}^{4}J$

Given:
Force, $F=1000N$
Distance, $s=10m$ opposite to the direction of force.

Work done is given by the force and displacement in the direction of force. Since displacement is opposite to the direction of force, it should be taken as negative.
$W=F\times -s$
$W=1000N\times -10m$
$W=-10000J=-1\times {10}^{4}J$
Magnitude of work done is:
$|W|=1\times {10}^{4}J$