mechanics Question
Question
A flywheel made of a thin ring 20 mm and 150 mm wide, with a mean diameter of 1.5 m. Calculate the time taken to come to rest from 10 revs/sec due to a frictional couple of 8 Nm. The density of steel is 7.8 Mg/m3 and the effects of spokes may be neglected.
Formula help
Pressure
1 bar = 100,000 N/m2
F = m. a
v = u + at
s = ut + ½ at2
v2 = u2 + 2as
Angular
T = I.
2 = 1 + t
= 1t + ½ t2
22 = 12 + 2
Relationship
s = r
v = r
a = r
Forces, Moments, and Power
Moment = Force x Perpendicular Distance from the Origin
Work Done = Force x distance
Power = 
P.E. = m g h
K.E. = ½ m v2
Friction
Ff = x R
Power loss = Fr x v
