Before you can just program that, you are going to have to know the physics formulas, and know how to do simple collision detection. The collision is simply a matter of checking if rectangle's overlap. The physics involves using the formulas for distance horizontally and vertically, and generating a vector or a point based on the calculations. I suggest you look up some physics stuff online. If I remember, the formula for the horizontal coord is distance = speed * time, so you would get the distance moved by multiplying the object's velocity times time. The vertical formula is distance = .5(9.8)time^2 for earth (9.8 is the gravitational constant for earth).
[This message has been edited by Qoy (edited December 17, 1999).]