a) Why are there no units attached to values of μ?

b)A force of 120 N is needed to push a box along a level road at a steady speed. If the force of gravity on the box is 250 N, what is the coefficient of kinetic friction between the box and the road?

1 answer

a
because it is a ratio of friction force to normal force

b
see answer to a above
friction force / normal force = 120/250