Relativity theory

a.) Draw a space-time diagram for a piston moving back and forth in a cylinder. (use the line of motion of the piston for the space coordinate)...a description of how one might make such a diagram would be sufficiant.
b.) Clocks A and B are synchronized and the clock A is sent on ten fast earth orbits and brought back. Now that the clocks are at rest again relative to each other, which of the following are true (Why?):
   1.) A is running slower than B
   2.) A is behind B in time
   3.) A is smaller than B
   4.) A is more massive then B