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Mechanics

Cool goIITian

Joined:	9 Oct 2007
Post:	73

25 Oct 2007 22:55:32 IST

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356

Energy conseravtion

None

WHen a body is placed on a sphere ( R radius) moving with W acceleration (horizontal)The body is sliding.We need to find the velocity at time of break oofff .......then the equation for energy conservation be.change in ...

potentil to kinetic ...........but it is given in th bokk like the following plz help

1/2mv^2 (K.E) +mWRsin

=mg(R-Rcos

)( P.E)

Whyhas he put mWRsin teeta ???????? plzzz help me

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Comments (3)

biki ....

Blazing goIITian

Joined: 5 Jun 2007

Posts: 978

25 Oct 2007 23:51:11 IST

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let angle made =

(as shown in figure)

let v = velocity just before falling

So at an instant just before falling---

mv²/r = mg.cos

_____(1).........where m = mass, r = radius of the sphere

or v²/r = g.cos

_____(1)

again change in K.E. = (1/2)mv² - 0 ......as initial velocity = 0

and loss in P.E. mg(r - r.cos

)

So (1/2)mv²= mg(r - r.cos

)

or v²/2 = gr (1 - cos

)

or v²/r = 2g(1 - cos

)

or g.cos

= 2g - 2g.cos

or 3g.cos

= 2g

or cos

= 2/3

= cos^-1(2/3)

biki ....

Blazing goIITian

Joined: 5 Jun 2007

Posts: 978

26 Oct 2007 10:04:40 IST

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i hope this will do...???
if you dont understand something....nudge me

viswesh Nrayanan

Cool goIITian

Joined: 9 Oct 2007

Posts: 73

26 Oct 2007 21:36:13 IST

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no ..........Here the spehear is accelerating..... i want it from ground frame]

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