Rotational Motion Question 211

Question: The moment of inertia of a body about a given axis is1.2kgm2 . Initially, the body is at rest. In order to produce a rotational kinetic energy of 1500 joule, an angular acceleration of25radian/sec2 must be applied about that axis for a duration of

Options:

A) 4 seconds

B) 2 seconds

C) 8 seconds

D) 10 seconds

Show Answer

Answer:

Correct Answer: B

Solution:

[b]

I=1.2 kg m2,Er=1500J

α=25rad/sec2,ω1=0,t= ? 

AsEr=12Iω2,ω=2ErI=2×15001.2=50rad/sec

 From ω2=ω1+αt

50=0+25t,t=2 seconds 



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