Question

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 come to rest is :

(A) 420 

(B) 280 

(C) 190 

(D) 16800

Answer 1

Correct option (B) 280

Explanation:

The correponding (Rev./sec), graph is :

Area under this curve gives the total number revolutions

= 1/2(8) (30) + (10 × 8) + (16) (10)= 280 revolutions