Posted by Rajan on .
A flywheel has an angular speed of 1200 rev/min when its motor is turned off. The wheel attains constant decelerations of 1.5 rad/s2 due to friction in its bearing. Determine the time required for the wheel to come to rest and the number of revolutions the wheel makes before it comes to rest

Dynamics 
Elena,
2π•f(fin)= 2π•f(init)εt
f(fin)=0, f(init) = 1200 rev/min =20 rev/s.
2π•f(init)=εt
t=2π•f(init)/ ε= 2π•20/1.5=83.8 s.
2π•N= 2π•f(init) •t  εt²/2.
N= f(init) •t  εt²/4π=
=20•83.8 – 1.5•(83.8)²/4•π =
= 838 rev.