Refer to the following information for the next two questions.
A "rocking box" apparatus can be used to determine coefficients of static and kinetic friction between a sliding block and the interior surface of the box. As the box is slowly rotated counterclockwise, the block of mass
m will just start to slide when the box makes an angle
θ with the horizontal. At this instant the box is stopped. Thus at angle
θ, the block slides a distance
d, hits the spring of force constant
k, and compresses the spring a distance
x before coming to rest.