(adsbygoogle = window.adsbygoogle || []).push({}); 1. A piece of metal is pressed against the rim of a 2.8- kg, 20- cm-diameter grinding wheel that is turning at 2000 rpm. The metal has a coefficient of friction of 0.75 with respect to the wheel. When the motor is cut off, with how much force must you press to stop the wheel in 20.0 s?

2. angular velocity w= (rpm*2*pi)/60

angular accel a= w/time

inertia I=mr^2

Torque T=Ia

F=T/r

3. Here is what I have...I'm not sure how to work in the coefficient of friction... I assumed that it might be T(mu)/r, but it doesn't seem to be right..

w=(2000*2*3.14)/60 =209.44

a=209.44/20 =10.47

I= 2.8*.1m =.028

T= 10.47*.028 =.293

F=.29/.1 =2.2 N

Again, I'm assuming all of the above is right, but I'm unsure of how to work in the coef of friction.

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# Homework Help: Stopping Grinding Wheel

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