Question

A 100 kg wooden crate rests on a level wooden floor. What is the minimum force required to move it at a constant speed across the floor? (coef. of static friction = 0.50; coef. of kinetic friction = 0.30)

Answer 1

This should help.

Answer 2

@CJS17 is right.
First you should find the limiting friction i.e. the friction need to move the block and then the summation of all the forces should be equal to zero for the block to move with a constant velocity. Thus, the kinetic friction should be equal to the force with which we push the block.