A box of books weighing 328N moves with a constant velocity across the floor when it is paged with a force of 385N exerted downward at an angle of 25.3 below the horizontal. Find muK between the box and the floor

Answer 1

the force increases the normal downward force.

Forcehorizontal=frictionforce=ma=0
385cos25.3=mu(328+385sin25.3)
solve for mu.