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Starting from rest, a fan takes five sec...

Starting from rest, a fan takes five seconds to attain the maximum speed of 40 rpm(revolutions per minute). Asuming constant acceleration find the time taken by the fan in attaining half the maximum speed.

A

20 s

B

2.5 s

C

10 s

D

2.0 s

Text Solution

Verified by Experts

The correct Answer is:
B
`tau = (pi(n_(2)-n_(1)))/(t)`
`omega_(2)=omega_(1)+alpha t`
`therefore t=(omega_(2))/(alpha)`
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