A block of mass m= kg can slide along a curved track as shown here.
The block, initially at a height h= meters above the ground is released. It slides
down a track which is all frictionless, except for a rough zone having a length of d= meters.
In this rough zone, there is friction between the block and the track with a 
= .
In either case, the block eventually hits the spring-stopper to the right. The spring has a a spring
constant k= N/m. How far does the spring compress when it brings the block to a stop?