a fan starts rotating from rest, when it complete 50 rotations its rate of rotation is 10 rotations/sec. what is the angular acc of it

t = 50rev. * 1s/10rev = 5 s.

acc. = (V2-V1)/t = (10-0)/5 = 2 rev/s^2.

2rev/s^2 * 6.28rad/rev = 12.56 rad/s^2.