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Bogdan [553]
3 years ago
14

a fan is rotating at 90 rpm.It is then switched off. It stops after 21 revolutions. calculate the time taken by the frictional t

orque is constant ​
Physics
1 answer:
fredd [130]3 years ago
6 0

Answer:

If the frictional torque is constant, the fan will slow down linearly from its original rotational speed of 90 rpm, equivalent to 1.5 rev/s. Linear slowdown implies that the average rotational speed until a complete stop is half of the top speed. Therefore the fan rotates at an average of 0.75 rotations per second. The time  t  to stop is therefore:

t=210.75  

=28  seconds

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