A computer disk is 8.0cm in diameter. a refrence dot on the edge of the disk is initially located at theta= 45 degrees.(adsbygoogle = window.adsbygoogle || []).push({});

The disk accelerates steadily for 1/2 second, reaching 2000 rpm, then coasts at steady angular velocity for 1/2 second.

what is the speed of the refrence dot at 1 second. answer is in m/s.

it seems to me that the first half second of this problem could be ignored, since after the first 1/2 second we stop accelerating and are in Uniform Circular Motion.

so I thought i would use v = ( 2(pi)r ) / T.

i knew my radius was .04m.

and to find T i did ( 2000 rev) * (1 min / 60 sec) = 33.33 rev/sec

my V ended being .0075 m/s this answer is wrong and im not sure if it is because i ignored the first half second of the problem, i just dont see how that ties into finding the velocity at 1 second. i figured that if it was coasting steadily at 2000 RPM it turns into a unifor circular motion problem

:yuck:

any help is apreciated, thanks.

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# Homework Help: Disk speed NON UNIFORM and UNIFOR CIRCULAR MOTION

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