Learning to build or repair a car would probably improve your understanding of thermodynamics, aerodynamics, momentum, etc. Likewise, writing a computer program that simulates the motion of a planet around a star or renders 3D graphics might improve your understanding of classical mechanics and any number of topics in math, just to name a few examples; cf.
This is not to mention that learning how to program a computer is just another tool to put in your bags of tricks for solving problems in any of the domains you mentioned (some better suited than others, of course).
http://www.amazon.com/Mindstorms-Children-Computers-Powerful...
http://www.amazon.com/Structure-Interpretation-Classical-Mec...
http://www.amazon.com/Turtle-Geometry-Mathematics-Artificial...
This is not to mention that learning how to program a computer is just another tool to put in your bags of tricks for solving problems in any of the domains you mentioned (some better suited than others, of course).