give the answer first..

JEE Mains 2015 Forum › Mechanics questions › give the answer first..

A pendulum bob (mass m)at its mean positon is given velocity v=√7gl/2 .Calculate the height at which it leaves circular path..
Just give the answer first,,,I want to confirm mine...

#Physics #Mechanics

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18 Answers

1

Prashant Shekhar ·2009-01-01 16:46:09

Well, Sankara.. the path should follow the direction of velocity which will be normal to the thread. And it leaves the circular path and enters a parabolic path.

In fact, there can be another interesting problem where you have to find the initial velocity given at the mean position of the ball such that it leaves the circular path and passes through the point of poivot during the parabolic path.

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62

Lokesh Verma ·2009-01-03 11:06:45

no sankara..

There will be 2 forces on the mass..

mg and T

T will be zero when it will just leave the circular path.....

mg will be downward... of which the component has to be taken...

i am sorry but mg/sinÎ¸ is a totally wrong concept.. it is not a concept at all.. it is a sin to think of force as that!

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3

msp ·2009-01-02 06:08:10

prashanth sir thnx for the diag

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3

msp ·2009-01-02 05:29:34

sir doesnt the centripetal force is mg/sinÎ¸

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11

Subash ·2009-01-02 05:22:03

yipee so my ans was correct

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24

eureka123 ·2009-01-01 22:22:18

i am finding it hard to diifferentiate b/w L and 2

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62

Lokesh Verma ·2009-01-01 22:06:23

I know that the contrast is very low.. but still try to see if it works :)

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24

eureka123 ·2009-01-01 21:48:47

sir but answer is 27l/64..............and i am getting 11 l/2

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62

Lokesh Verma ·2009-01-01 20:52:58

eureka.. the height is 3l/2

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3

msp ·2009-01-01 10:58:08

the ans is 3l

oops mistake in my calculations

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3

msp ·2009-01-01 11:50:35

the dotted line shows the trajectory of hte particle

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msp ·2009-01-01 11:49:16

yes eureka i am wrong with my ans without understanding the question clearly.

i will post the diagram that would help u

from where is the height to be measured

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3

msp ·2009-01-01 11:20:44

can u post ur soln so that we can discuss wat mistake done by us.

my soln.

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24

eureka123 ·2009-01-01 11:14:49

my answer is diff from u................................

but one thing common in all......we all are getting wrong answer.......correct answer is 27/16l

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3

msp ·2009-01-01 11:11:21

my answer is true if l is the length of the suspension of the bob.

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msp ·2009-01-01 11:10:15

post ur answer. waiting for ur reply.

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11

Subash ·2009-01-01 11:01:56

hey give us the correct ans

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11

Subash ·2009-01-01 10:58:09

3l/2

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Your Answer

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