Physics of Dance Movements
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At its best, dancing appears fluid and effortless. To an observer, it may seem that the dancer is simply leaping, turning and floating through space. The skilled dancer understands the mechanics involved and how those can be used to influence performance results. With some knowledge of the physics behind basic dance movements, a dancer can learn to jump higher, spin faster and move more quickly.
The forces acting on an individual dancer create a push-pull relationship between the dancer and the surrounding space. The force you exert on the floor is affected by the direction and magnitude of the force. When balancing in releve, or on your toes, you are exterting a force against the floor that is equal to the force of gravity being exerted on you. This results in a zero sum force acting on the body placing you in your center of gravity.
Moving in a constant direction, as in performing dance combinations across the floor, creates momentum. Momentum is mass in motion. The amount of momentum depends on the amount of mass moving and how fast that mass is moving. Developing strength in your legs will move you across the floor quicker. Combinations across the floor produce linear momentum, while turns involve angular momentum. Torque and rotational inertia are the physics principles that can affect the speed and balance of your spin.
Torque and Turns
Torque is important in the production of many dance turns. This can come from the friction produced by pushing off the floor. The harder you push off the floor, the faster you spin. Torque also can be produced by the leg. The extension and retraction of the leg in turns, such as in a fouette, affects the rotational inertia of the turn. In other words, you slow down when the leg is extended and speed up when the leg is retracted.
Graceful, elegant leaps in dance are achieved by overcoming gravitational pull and creating the illusion of a raised center of gravity. The height of jumps is affected by force and speed. The more mass, or strength, you have in your legs, the more power you are able to apply to the jump. That coupled with timing can create a jump that appears to float in the air. A grande jete, for example, is shaped as a parabola. Time the jump to raise your center of gravity at the peak of the parabola and you will create the vision of gliding through space.
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