Force and Partical System

This week we were introduced the application of objects in coding and it is amazing that me have this function. We get to construct one class and simply call it whenever we need it again.
This week's assignment is to use the object function and create a couple of balls and apply forces to them using Newton's Laws. Furthermore, we should also make the program responsive to mouse clicks and key strokes.

Here's a snapshot of what I did:

1. click on a ball to lift it and change its color
   
2. click and drag to move the ball
   
3. press "SPACE" key to lift them all
   
4. press "1" to pause/resume