Question

A bicyclist comes to a skidding stop in $10m$. During this process, the force on the bicycle due to the road is $200N$ and is directly opposed to the motion. The work done by the cycle on the road is

• A. $+2000J$
• B. $200J$
• C. $zero$
• D. $20,000J$

Answer 1

The correct option is C $zero$

Work done by the road on the cycle is

$W=F\times s=-200N\times 10m=-2000J$

Negative sign indicates that the direction of the force and the displacement is opposite.

The cycle applies an equal and opposite force on the road. But as the displacement of the road is zero, work done by the cycle on the road is $zero$.