(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

A 3.10 kg, 31.0-cm-diameter disk in the figure is spinning at 300 rpm, how much force must a brake apply that is perpendicular to the rim of the disk to bring the disc to a halt in 2.4 s.

2. Relevant equations

t=i*alpha wf=0+alpha*t t=fr*sin(theta)

3. The attempt at a solution

i=1/2mr^2=.24

wf=0+alpha*t wf=0 w0=300 rpm=31.4 rad/s t=2.4 s alpha=-13.1 rad/s^2

t=i*alpha=-3.1 n*m

t=fr*sin(theta) theta=90 degress

t=fr

-3.1=f*.155 r=15.5 cm=.155 m

f=-20 n

Don't know what i'm doing wrong but it's not the correct answer.

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# Friction force on disk

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