A flywheel has a mass of 20 kg and a radius of gyration of 100 mm. Its angular kinetic energy when rotating at 10 rev/s is:
A) 2J
B) 20J
C) 790J
D) 7896J

Question

Quizplus · Accepted Answer

The formula for angular kinetic energy is:
KE = (1/2)Iω^2
where I is the moment of inertia and ω is the angular velocity.
The moment of inertia of a flywheel is given by:
I = mr^2
where m is the mass and r is the radius of gyration.
Substituting the given values, we get:
I = (20 kg)(0.1 m)^2 = 0.2 kg m^2
ω = 2πf = 2π(10 rev/s) = 20π rad/s
KE = (1/2)(0.2 kg m^2)(20π rad/s)^2
KE = 790 J
Therefore, the answer is C, 790J.

A Flywheel Has a Mass of 20 Kg and a Radius