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Angular velocity Question?
After switching off an electric fan it's angular velocity decreases by 50% after rotating 36 turns. How many more turns it will rotate before coming to rest? (Assume the motion is under constant angular deceleration)
1 Answer
- AnthonyLv 77 years agoFavorite Answer
for the first 50%
Final velocity = v = u/2
distance = s = 36pid
initial velocity = u
Use v^2 = u^2 + 2as
u^2/4 = u^2 + 72pida
-3u^2/4 = 72pida
-3u^2 = 288pida
-3u^2/288pid = a
-u^2/96pid = a
.
for the final 50%
U = u/2
V= 0
A = -u^2/96pid
use V^2 = U^2 + 2AS
0 = u^2/4 - 2Su^2/96pid
-u^2/4 = -2Su^2/96pid
S = (-u^2/4)*96pid/2u^2 = 96pid/4 = 12pid
and pid = 1 rev
S = 12 revolutions = Answer
