Question

A box of books weighing 325 N moves at a constant velocity across the floor when the box is pushed with a force of 425 N exerted downward at an angle of 35.2 below the horizontal. Find Uk between the box and the floor?

Answer 1

0,61

Explanation:

if there are no acceleration (velocity =constant), it means that the forces of the system are all balanced. Hence the pulling force
`Fx= F xx cos alpha = 425 N xx 0,817 =347 N`
is equal to resistance force to the movement
`F= f_a xx (F_w+ F sen alpha)= f_a xx (325 N + 425N xx 0,576) = f_a xx 570 N`
so, by equalling the two forces, you have `f_a=(347N)/(570N) =0,61` that is the friction coefficient