Dance is artistic motion of the human body.
(Cirque du Soleil)
Tommie Smith & John Carlos
Mexico City 1968 Olympics
Physical motion is governed by Newton’s three laws of motion:
Principle of Inertia
Force = Mass x Acceleration
Action & Reaction
We’ll see how these laws apply to dance.
Sir Isaac Newton
(1643 – 1727)
Newton’s First Law of Motion
An object moves with constant, uniform motion until acted on by a force.
First Law (Full Version)
An object at rest remains at rest &
an object in motion remains
in uniform motion*,
unless a force acts on the object.
*Moving in a straight line with constant speed.
First Law is also known as principle of inertia.
Demo: Tablecloth Pull
Due to the vase’s inertia it remains at rest since almost no force acts on the vase if one pulls quickly & straight.
Demo: Riding Light Rail
When a moving train stops, you continue moving forward.
When the stopped train starts moving again, you remain stationary and are thrown backwards.
In both cases, it’s due to your inertia.
Follow-through is a good example of the principle of inertia.
An object won’t move until a force acts on it so long hair trails behind as head turns.
Hair then remains in motion even after the head stops turning.
The Newton is metric unit of force (about 1/5 pound).
When several forces act on an object, the forces add together.
Sum of forces called net force or total force
If an object is at rest then the net force must be zero. Similarly if in uniform motion.
When this happens we say that forces “balance.”