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

Question

Bogdan [553]

2 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] · Answer 1 · 2022-07-26T00:46:11+03:00

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