momentum and Area
It might seem surprising that a particle moving
in a straight lines has angular momentum.
Conservation of angular momentum
L = r
X m v
In the absence of a net external torque acting on a system,
its angular momentum remains constant.
Kepler's second law states:
Does a free particle moving in a straight lines
sweep out equal area? (with respect to any origin.)
Press start to start the animation, and let the show
A black dot will move freely from left to right.
Different color shows the area it sweeps out
Do all the areas have the same size?
with respect to some fixed points.
Click within each area and see what will happen.
Certainly, from mathematic equation, we know
Area of a triangle = width * height /2
All the areas have the same height,
and the same width (=Vx*dt).
Your suggestions are highly appreciated!
E-mail : please click firstname.lastname@example.org
Author¡GFu-Kwun Hwang, Dept. of physics, National Taiwan Normal University
Last modified :