Question

If you exert a force of 60 N on a car, it moves at a constant velocity. (i.e there is a frictional force of 60 N) What is its mass when you exert 80 N on it, it accelerates from rest to 2.0 m/s in 100 seconds?

Answer 1

v=at => a =v/t =2/100=0.02 m/s²

0=F1-F(fr) =>F(fr)=F1,
ma=F2-f(fr)= F2-F1,
m=( F2-F1)/a=(80-60)/0.02=1000 kg