A flywheel is a solid disk that rotates about an axis that is perpendicular to t

Question

A flywheel is a solid disk that rotates about an axis that is perpendicular to the disk at its center. Rotating flywheels provide a means for storing energy in the form of rotational kinetic energy and are being considered as a possible alternative to batteries in electric cars. The gasoline burned in a 337-mile trip in a typical midsize car produces about 2.77 x 109 J of energy. How fast would a 25.8-kg flywheel with a radius of 0.226 m have to rotate to store this much energy? Give your answer in rev/min.

Explanation / Answer

here,

mass , m = 25.8 kg

radius , r = 0.226 m

let the angular speed of fly wheel be w

kinetic energy , KE = 2.77 * 10^9 J

KE = 0.5 * I * w^2

KE = 0.5 * m * r^2 * w^2

2.77 * 10^9 = 0.5 * 25.8 * 0.226^2 * w^2

soling for w

w = 6.48 * 10^4 rad/s

w = 6.2 * 10^5 rev/min

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