When a celling fan is switched off, its angular velocity falls to half while it makes `36` rotations. How many more rotations will it make before coming to rest ?

Options

A. 36
B. 24
C. 18
D. 12

Answer

D

Explanation

Using, `omega_(2)^(2)-omega_(1)^(2)=2 alpha theta,` we get
`(omega//2)^(2)-omega^(2)=2alpha(36xx2pi)" …(i)"`
Similarly, `0^(2)-(omega//2)^(2)=2alpha(nxx2pi)" …(ii)"`
Dividing Eq. (i) by Eq. (ii), we get
`(-(3)/(4)omega^(2))/(-(omega^(2))/(4))=(36)/(4)rArr n=12`