Rotational Kinetic Energy Calculator

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Choose whether to type in a known moment of inertia, or let the calculator work it out for a standard rigid-body shape.
The rotational inertia of the body about its spin axis. 1 lb·ft² = 0.04214 kg·m².
How fast the object spins. 300 RPM = 31.42 rad/s = 5 Hz.
RPM
Rotational kinetic energy
154.2126

KE = 0.5 * I * omega^2

Energy unitJ
Moment of inertia0.3125kg*m^2
Angular velocity31.4159rad/s
Speed300RPM
Angular momentum9.8175kg*m^2/s
Rotational KE154.2126
Angular Momentum9.8175

Rotational kinetic energy: 154.2126 J

  • The moment of inertia is 0.3125 kg*m^2 and the angular speed is 31.42 rad/s (300.0 RPM).
  • The angular momentum stored is 9.8175 kg*m^2/s. Doubling the spin rate would quadruple the kinetic energy, since it scales with omega squared.
  • This is roughly equivalent to 36.9 calories, similar to a bicycle wheel spinning at speed.

Next stepTo find how much torque is needed to spin up to this speed over a given time, divide the angular momentum by the spin-up time.

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