A 1.5 kg box is initially at rest on a horizontal surface n at t = 0 a horizontal force F = (1.8t)i N (with t in seconds) is applied to the box. The acceleration of the box as a function of time t is given by a = 0 for 0 < t < 2.8s and a = (1.2t – 2.4)i m/s2 for t > 2.8 s.
(a) What is the coefficient of static friction between the box and the surface?
(b) What is the coefficient of kinetic friction between the box and the surface?