A student, crazed by final exams, uses a force P of magnitude 80 N and angle ?

Question:

A student, crazed by final exams, uses a force P of magnitude 80 N and angle ? = 70o to push a 5.0 kg block across the ceiling of his room (Figure). If the coefficient of kinetic friction between the block and the ceiling is 0.40, what is the magnitude of the block's acceleration?