Balance Main Page
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To simply put it,
balance means that the dancer's body is in equilibrium with no
inclination to fall (due to the force of gravity). There is no
net force, which implies no change in momentum and no net
torque, which implies no change in angular momentum. The force
on the floor from the dancer is equal to the force of the
floor upon the dancer. All of these forces go through the
center of gravity, and this spot needs to be directly over the
dancer's contact spot on the floor. If the center of gravity
is not over this spot, the dancer will topple over. With this,
if the area of contact is smaller, then it is more difficult
to balance. Think of a ballerina balancing "en pointe;" the
contact area of the shoe is quite small, so keeping the center
of gravity over this spot is very difficult. Balancing isn't
as easy as it seems!
Images from cynthiawoong.com
and web.hep.uiuc.edu
Some useful
vocabulary:
- Equilibrium: State in
which opposing forces are balanced
- Net Force: Sum of all forces
- Momentum: Quantity of
mass in motion
- Torque: Twisting force that tends
to cause rotation
- Angular
Momentum: Quantity of rotation
of a body