When a ceiling fan is switched on, it makes 10 revolutions in the first 3 seconds. Assuming a uniform angular acceleration, how many rotations it will make in the next 3 seconds?

When a ceiling fan is switched on, it makes 10 revolutions in the firs

1.	When a ceiling fan is switched on, it makes 10 revolutions in the first 3 seconds. Assuming a uniform angular acceleration, how many rotations it will make in the next 3 seconds?
Answer» 10 20 30 40 Solution :In first three seconds , ANGLE rotated `theta = 2pi//V = 2pi XX 10 ` Using , `theta = omega_(0) t + (1)/(2) alpha t^(2)` `therefore 2 pi xx 10 = 0 + (1)/(2) alpha xx 3^(2) = (9)/(2) alpha "" …. (i)` For the rotationof fan in next three seconds , the total time of rotation = 3 + 3 = 6 s Let total NUMBER of rotation = N Then angle of rotation , `theta = 2 pi N` `therefore 2 pi N =0 + (1)/(2) alpha xx 6^(2) = 18 alpha "" .... (II)` Dividing (ii) by (i) , we get N = 40 No. of ROTATIONS in last three seconds = 40 - 10 = 30 rotations