# Dynamics

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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 -

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.

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