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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 resulating variation of the revolution/minute time is shown in Fig. The total number of revolutions of the fan before it comes to rest is

A

`280`

B

`380`

C

`420`

D

`160`

Text Solution

Verified by Experts

The correct Answer is:
A
Total number of revolutions = area under `n -t` graph
`= (1)/(2) xx 8 xx (1800)/(60) + 8 xx (600)/(60) + (1)/(2) xx 16 xx (600)/(60)`
`= 120 + 80 + 80 = 280`
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