Question

A table fan rotating at a speed of `2400` rpm is switched off and the resulting 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. 420
B. 280
C. 190
D. 16800

Answer 1

Correct Answer - B
The corresponding (Rev/sec) graph is (Rev/sec)

Area under this curve gives the total number revolutions
`Delta = (1)/(2) (8)(30)+(10 xx8)+(16)(10)`
= 280 revolutions
D is only correct option