Question

a window washer pushes his scrub brush up a vertical window at a constant speed by applying a force f. the brush weighs 8N and the coefficient of friction is 0.4. calculate a) the magnitude of the force f. b) the normal force exerted by the window on the brush.

Answer 1

If v=const => a=0
f=F(fr)+mg
If f is directed vertically N=0 => F(fr)=μN=0
=> f=mg

Answer 2

no