This java applet show you how to use the law of reflection (for optics) in playing pool.
A ball bouncing off the bank of a pool table behaves like a light ray
reflecting off a mirror.
There are two colored balls; red and blue.
How to play?
More information will be provided If you select level1 or level2.
Try it and find out the physics behind the game.
(For collision between two balls, please check out 2D
Collision java applet)
John Botsford wrote:
>
> The law of reflection can only be used in
billiards to
> approximate the angle of reflection for
a billiard ball. Since
> the rails of a pool table are rubber, the
ball will sink into
> the cushion to varying degrees depending
on the velocity of the
> ball. This amount that a ball sinks
into the cushion changes
> the angle of reflection. For instance,
the faster a ball is
> moving when it hits the rail, the sharper
the angle of
> reflection will be. The law of reflection
is a close
> approximation only if the ball is moving
relatively slowly. The
> other thing that affects the angle of reflection
is the spin on
> a ball. In the case of the cue ball,
spin is often purposely
> mparted to the ball by striking it off center
in order to change
> where the cue ball will end up. As
for object balls, spin is
> imparted to them by contact with other objects
(balls and
> rails). This spin also changes the
angle of reflection.
>
Yes. It is true that the law of reflection
is only an approximation of what really happened!
The effect of rubber and the spining effect
also can be simulated
if we know the spring constant and apply conservation
of momentum,
energy and angular momentum. But that would
be too complicate to
the students who just learn physics.
The purpose of our animation is for teaching.
That is why I
simplify the problem and the result are still
very similar to what
really happened. Thank you for your
comments. Could I add your
comments to the end of the web pages?
Regards!
Author¡GFu-Kwun Hwang, Dept. of physics, National Taiwan Normal University
Last modified : More physics related java applets