Question

A 60kg person exerts a horizontal force of 200N and pushes a 90kg object through a distance of 6m along a horizontal floor . He does that at a constant velocity of 3m/s. What is the force of friction?

Answer 1

According to the Second Newton’s Low
F ⃗=ma ⃗
In our case
v_x=const → a_x=0
We have
200-F_f=0 → F_f=200 N