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Grade 9Mechanics

Starting From Rest,a fan takes 5 seconds to attain the maximum speed of 400rpm. Assuming constant acceleration, find the time taken by the fan in attaining one eighth of it's maximum speed.

Profile image of GAMING WITH KRISH
7 Years agoGrade 9
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1 Answer

Profile image of GAMING WITH KRISH
7 Years ago
Let the angular  acceleration be alpha. According to the question, 
400rpm=0+5*(alpha )
Let t be the time taken in attaining  the speed of 50rpm which is one eighth of the maximum speed 
Then,  50rpm=0+(alpha)t
Dividing 1st equation by second equation, 
8=5÷(t)
=> t=1.6 seconds
 
Then, 200rpm=0+(alpha)t