A circular solid disc of uniform thickness 20 mm, radius

A circular solid disc of uniform thickness 20 mm, radius 200 mm and mass 20 kg, is used as a flywheel. If it rotates at 600 rpm, the kinetic energy of the flywheel, in Joules is

K.E. of fly wheel =	1	ω²
	2

where, I =	mR²	=	20 × 0.2²	= 0.4 kg- m²
	2		2

ω =	2πN	=	2 × π × 600	= 62.83 rad/s
	60		60

K.E.=	1	× 0.4 × 62.83² = 790 J
	2