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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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Knowledge Check

  • 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

  • A fan is rotating with a speed of 450 rec/minute. Afer being switched off it comes to rest in 10s. Assuming constant angular deceleration, calculate the number of recvolutions made by it before coming to rest.

    A
    37.5
    B
    37
    C
    38.5
    D
    None

  • A wheel has a speed of 1200 revolution per minute and is made to slow down at a rate of 4 rad//s^(2) . The number of revolutions it makes before coming to rest is

    A
    `143`
    B
    `272`
    C
    `314`
    D
    `722`

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