Hi, I\'m having some major physics difficulty! I got the first part, however I c

Question

Hi, I'm having some major physics difficulty! I got the first part, however I can't seem to get the second part. Help would helpful :)

(a) A centrifuge is a common laboratory instrument that separates components of differing densities in solution. This is accomplished by spinning a sample around in a circle with a large angular speed. Suppose that after a centrifuge in a medical laboratory is turned off, it continues to rotate with a constant angular deceleration for 12.1 s before coming to rest.

(a) If its initial angular speed was 3550 rpm, what is the magnitude of its angular deceleration? 4.8898

(b) How many revolutions did the centrifuge complete after being turned off?

I need help with (b) !!!! Thank you in advance

Explanation / Answer

We find the angle travelled by the centrifuge before it comes to rest.

v^2 = u^2 + 2as

v = final rps = 0

u = initial rps = 3550 / 60 = 59.16 rps

a = -4.88 rev /s^2

thus,

s = (59.16)^2 / (2 x 4.88) = 358.59 radians

Thus, number of revolutions = 358.59 / 2*pi = 57.07 revolutions

Centrifuge had turned 57.07 revolutions before coming to a stop

hope this helps. please rate it ASAP. Thanks

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