Arrow, ball... same thing. Due to the relative sizes of the objects involved in the physical simulation, we consider all these objects as particles and manipulate them as such. In other words, there's an answer to your question just a few posts down, in a thread called "Ball physics" or so.

[Edit: The thread's actually called Ball in a football game.]

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Thanks to Kylotan for the idea!

[edited by - Oluseyi on March 18, 2002 10:19:10 PM]

In the absence of air resistance or any other retarding forces, then the motion of the arrow is given by the equations of projectile motion . The path of the arrow is given by:

                              gy = (tan  theta0)x - ------------   x2                    2(v0cos  theta0)2       

Alternatively, if you want this expressed in terms of vertical and horizontal velicities, then

vy = v0sin theta0 - gt
vx = v0cos theta0

If you'd like to know the range of the arrow, that is given by:

    v02R = --- sin  (2theta0)     g       

where:
v0: initial speed of arrow
theta0: firing angle (from horizontal)
g: gravitational acceleration
t: time
x: horizontal displacement from firing point
y: vertical displacement from firing point

I hope this helps!

Timkin

[edited by - Timkin on March 18, 2002 10:42:57 PM]