potential energy/ momentum

Question

Mary applies a force of 78 N to push a box with an acceleration of 0.47 m/s². When she increases the pushing force to 86 N, the box's acceleration changes to 0.64 m/s². There is a constant friction force present between the floor and the box.

What is the mass of the box in kilograms?

What is the coefficient of kinetic friction between the floor and the box?

Answer 1

In each case i = 1, 2, the box acceleration a_i is related to the difference of Mary's pushing f_i and the frictional resistance μmg as ma_i = f_i – μmg. Solve these 2 equations for the 2 unknowns, box mass m and friction coefficient μ.