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Mechanics

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9 Jan 2007 21:32:57 IST

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circular Motion

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An object is tied with string of length L rotating in circular motion where end of string is on center. at the bottom its velocity is u what will be change in velocity when it reaches horizontal point.

This problem has come in screening IIT JEE 1998

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ashish banga

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10 Jan 2007 00:15:56 IST

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use energy conservation law

1/2mu^ = 1/2mv^ + mgL

anni.kalya

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10 Jan 2007 08:48:37 IST

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use conservation of energy,

1/2mu^2=1/2mv^2 + mgL

therefore v=

u^2-2gL.

change in vel= u-v

cvramana

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10 Jan 2007 21:24:15 IST

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The magnitude of the velocity at horizontal position can be found using conservation of energy.

-mgh = (mv² - mu²)/2

which gives v = Ö(u² - 2 gh).

Now change in velocity is Dv = Ö(v² + u²) , because both are perpendicular to each other.

Therefore Dv = Ö(v² + u²) = Ö( 2u² - 2gh) and its direction can be obtained by

Tan a = v / u

If it is only change in speed then the answer is v - u.

vinu

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11 Jan 2007 09:16:44 IST

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Tan ?= -u/v .(change in v= -vi +uj )

cvramana

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11 Jan 2007 10:17:23 IST

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Here minus sign has no importance. Because you have not given any direction initially as positive or negative.

you_saket

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11 Jan 2007 11:21:27 IST

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what is diffrance b/w rotational motion&circular motion.

vinu

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11 Jan 2007 20:02:01 IST

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Same as the difference b/w rotation & revolution.

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