A horizontal force of 90.7 N is applied to a 40.5 kg crate on a rough, level surface. If the crate accelerates at 1.08 m/s, what is the magnitude of the force of kinetic friction (in N) acting on the crate?

Mhide,

if the mass of 60 kg is having an acceleration of 1.2 m/s², we have:

F = m . a

60 x 1.2 = 72 N

That is, the resultant force is 72 newtons.

If the applied force is 95 N, we come to the conclusion that 95 - f = 72

Or,

f = 23 newtons, or 23 N, of kinetic friction.