Problem 6-11 Dynamics with friction

A child is sliding down a water slide inclined at $25^\circ$ to the horizontal. The coefficient of kinetic friction between the child and the slide is $0.10$. What is the magnitude of the acceleration of the child? (Hint: $F_N$ is not equal to $mg$.)

The FBD for this problem is:

(A)

(B)

(C)