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Ask iit jee aieee pet cbse icse state board community Community Discussion Question: circular motion(simple one)
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[Post New]9 Jan 2008 15:53:29 IST
    Subject: circular motion(simple one)
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savvej (214)

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what wiil be the duartion of a day if the earths radius is reduced to half?
plz give me the ans along with proper explaination of the concept.


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[Post New]9 Jan 2008 16:14:29 IST
    Subject: circular motion(simple one)
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master_purav (1341)

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Considering earth as a solid sphere

Moment of Inertia of Earth is proportional to r^2

According to law of conservation of angular momentum:

Iw = I'w'

I/T = I'/T'

T'/T = I'/I

T'/T = (r'/r)^2 = 1/4

T' = T/4 = 24/4 = 6

Thus it would be a 6 hour day....
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"There are either many different universes or many different regions of a single universe, each with its own initial configuration and, perhaps, with its own set of laws of science. In most of these universes the conditions would not be right for the development of complicated organisms; only in the few universes that are like ours would intelligent beings develop and ask the question: "Why is the universe the way we see it?" The answer is then simple: If it had been different, we would not be here!"

From Stephen Hawking's 'Breif History of Time'
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[Post New]9 Jan 2008 16:15:46 IST
    Subject: Re:circular motion(simple one)
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pratyush.pande (318)

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see first of all it is not a question of circular motion ...it is from rotational mech.
 
According to law or conservation of angular momentum
 
I1w1 = I2w2    --(1)
Earth can be considered as a shpere so I = 2/5 Mr2
Now since the radii is halved  I will become I/4
Using this in eqn 1
I*w = I/4*w2
w2 = 4w
now w = 2 pi/T
w inc four times so T becomes T/4
so duration of day = 24/4 = 6 hrs
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[Post New]10 Jan 2008 08:04:28 IST
    Subject: Re:circular motion(simple one)
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savvej (214)

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thnx to everyone rated u all. (this was a question in our circular motion objective assingment)


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