Question

A bicycle is upside down for repairs. The owner spins up the back wheel so it rotates at 116 rpm. If friction causes angular deceleration of -0.8 rad/s², how long does it take for the wheel to come to rest?

2 sig figs, units (s)

Answer 1

given

_o = 116 rpm

= 12.147 rad/sec  

_f = 0 rad/sec

= - 0.8 rad/s²

_f² = _o² + 2

0² = 12.147² + 2 x ( - 0.8 ) x

147.54 - 1.6 = 0

= 147.54 / 1.6

= 92.212 rad

using equation

= 1/2 ( _o + _f ) t

92.212 = 0.5 x ( 12.147 + 0 ) t

t = 92.212 / 0.5 x 12.147

t = 15.182 sec

so in t = 15.182 sec it take for the wheel to come to rest.

answered by: anonymous