A magnetic computer disk 8.0 cm in diameter is initially at rest. A small dot is painted on the edge of the disk. The disk accelerates at 600 rad/ s^2 for 1/2 s, then coasts at a steady angular velocity for another 1/2 s . a) What is the speed of the dot at t = 1.0 s?(adsbygoogle = window.adsbygoogle || []).push({});

b)Through how many revolutions has it turned?

for a) i kept getting the answer wrong:

i did :

d=8.0cm

so r=4.0 cm

ti=0s

tf=0.5s

a=600 rad/s^2

vi=(2)(pi)(4.0cm) / 1.0s

so; vi=25m/s

and for part b)

i think you have to use the kinematic equation after you get vi.. i'm not sure tho.. am i right?? please help. thanks in advance!

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# Homework Help: Circular motion of a cd

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