a man pushes a packing case which has a total mass of 50 kg across a floor at a constant speed of 0.4 m s-1 by exerting a horizontal force of 100 N.

(a) what was the resultant force on the case?

> F = ma
F = 50 * 0
F =0

(b) what was the frictional force acting on the case?

> 0 (frictional force is the same as resultant force?)

(c) if the force exerted by the man is increased to 120 N, what will the acceleration be?

> F = ma
120 = 50 * a
a = 120 / 50
a = 2.4 m s-2

1 answer

friction force=100, constant speed

120-100=ma
solve for a