Question

A woman attempts to push a box of books that has mass m up a ramp inclined at an angle α above the horizontal. The coefficients of friction between the ramp and the box are μs and μk. The force F⃗  applied by the woman is horizontal.

Assume that μs is less than this critical value. What magnitude of force must the woman apply to keep the box moving up the ramp at constant speed?​

Answer 1

If the box moves, kinetic friction acts on the box by the incline. Hence we use coefficient of kinetic friction in our equation of motion for the box and find the required force applied as shown below