Question

a fan rotate with a speed of 450rev/min after switch off it comes to rest in 10 second assuming constant angular acceleration ,calculate the number of revolution made by it before coming to rest​

Answer 1

Here; f = 450 rev/ min = 450/60 rev/s

f. = 15/2 rev/s

Therefore the angular velocity w. = 2π f•

= 15π rad / sec at t= 10s, w = 0

Therefore Angular acceleration

a=w-w./t

= w + 1/2 at^2

= 15π * 10 - 1/2 (3π/2) 10^2

= 150-75m = 75π rad

Therefore No. of revolution = •/2π = 75/ 2π

= 37.5