How long does it take to rotate? Physics

[BeatMCAT]

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So, quick question: How long does it take for a 33 rpm record to rotate once, at constant speed?

.033 seconds, 1.82 seconds, .29 seconds or 3.33 seconds.

So I went with this formula. v=2piR/T. and then solve for T, however we are not given the radius, so how would I go on to approach this. Am I just overlooking something really basic? Thanks!

 

[salim271]

You dont need the radius, they tell you the rpm, rotations per minute. So its 33 rotations/minute.

33 r/min x (1 min/60 sec) = a little more than one half a rotation per second. If it was 1/2 a rotation per second, then every 2 seconds would be one rotation. Its more, so the answer is less. 1.82 seconds a rotation.

Edit: You could also use the reciprocal of .55 to get about 1.82.

 

[justhanging]

So, quick question: How long does it take for a 33 rpm record to rotate once, at constant speed?

.033 seconds, 1.82 seconds, .29 seconds or 3.33 seconds.

So I went with this formula. v=2piR/T. and then solve for T, however we are not given the radius, so how would I go on to approach this. Am I just overlooking something really basic? Thanks!

rpm, stands for revolutions per minute.

 

[BeatMCAT]

Thank you!