Question

A 1200 kg car on a horizontal surface starts from rest and accelerates uniformly to 72 km/h in 20.0 s. Friction exets an average force of 450 N on the car during this time.

a) what is the net work done on the car
b) how far does the car move during this acceleration


now i knoq W=fxd but how else could i get it!!!! and how does the friction work in?

Answer 1

I know I'm 10 years late to this problem, but there's more steps to the problem that are missing, and friction doesn't come into play until those problems. Change km/h to m/s to get 20m/s, then KE=(1/2)mv^2 is the formula. The answer comes out to 2.4e5 J.