Question

An electric fan rotating at 3 rev s-1 is switched off. It comes to rest in 18.0 s. Assuming deceleration
to be uniform. How many revolutions did it turn before coming to rest?
A. 30 rev
B. 27 rev
C.40 rev
D. 10 rev

Answer 1

Answer:

decc. = 3/18 2pi per sec. sq.

angle made = 3× 2 pi × 18 - 1/2 (3/18) 2pi 18×18

so

rev made= 3×18 - 27 = 54-27 = 27 rev