Question

A student, crazed by the first physics Midterm, uses a pushing force of
80 N angled at 70° to push a 5.0 kg book across the frictionless ceiling
of his room.
a. What is the block's acceleration?
b. What is the force of the ceiling on the book?

Answer 1

Is the force applied at 70 degrees to the ceiling or the surface normal?

I assume it is 70 degrees to the ceiling, otherwise the brick would fall. The normal force on the ceiling is then 80sin70-5g = 26.1 N
(That is the answer to part (b))

The component along the ceiling is then
80 cos70 = 27.4 N

Acceleration = 27.4 N/(mass)= 5.47 m/s^2