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A table fan, rotating at a speed of 2400...

A table fan, rotating at a speed of 2400 rpm, is switched off and the resulting variation of the rpm with time is shown in the figure. The total number of revolutions of the fan before it comes to rest is

A

420

B

190

C

280

D

380

Text Solution

Verified by Experts

The correct Answer is:
C
Area under `n-t` graph will give total number of revolution before coming to stop
Area = Total number of revolutions
`=(1)/(2)xx8xx((1800)/(60))+8xx(600)/(60)+(1)/(2)xx16xx((600)/(60))`
`=120+80+80`
`=280`.
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