A steel block of mass 12kg starts from rest at the top of a smooth frictionless track, 2.5m above the horizontal ground. After reaching the bottom, it moves onto a rough horizontal surface and finally comes to rest after travelling 10m on that surface.
a. (a) Calculate the speed of the block at the bottom of the track.
b. (b) Determine its kinetic energy at the bottom.
c. (c) Assuming the horizontal surface offers a constant frictional force, calculate the magnitude of this frictional force.