A cyclist comes to a skidding stop in `10m`. During this process, the force on the cycle due to the road is `200N` and is directly opposite to the motion.
a. How much work does the road do on the cycle?
b. How much work does the cycle do on the road?

Explanation

Workdone on the cycle by the road is the work done by the stopping (frictional) force on the cycle due to the road.
a) The stopping force and the displacement make an angle of `180^(@)` (`pi`rad each other. Thus, work done by the road,
`W_(r) = Fdcostheta`
=`200 xx 10 xx cospi`
`-2000J`.
it is this negative work that brings the cycle opposite force acts on the road due to the cycle. Its magnitude is 200N. However, hte road undergoes no displacement. Thus, work done by cycle on the road is zero.