A phonograph record slows from an initial 45 rpm at a rate of .05 rad/s^2.(adsbygoogle = window.adsbygoogle || []).push({});

a) how long does it take to come to rest???

orig rotational velocity = 45 rpm = 4.71 rad/sec

acc = -.05 rad/s^2

0 = 4.71 rad/s + (-.050 rad/s^2) t

t = 94.2 s

b) How many revolutions does it make before stopping???

(w + w)/2 = (4.71 rad/sec)/2 = 2.355 rad/s * 94.2 s = 221.84 rads =

35.31 rev

Last one for the week. How does this look???

Thanks agaiin

Nautica

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# Homework Help: Rotational Kinematics

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