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Blazing goIITian

Joined:	19 Mar 2012
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5 Jun 2012 17:10:41 IST

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263

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FIND THE ACCELERATION OF BLOCK OF MASS M . ALL SURFACES ARE FRICTIONLESS AND PULLEYS AND STRINGS ARE LIGHT..................................

Comments (7)

Aman Sharma

Cool goIITian

Joined: 29 May 2012

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5 Jun 2012 17:18:00 IST

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For block of mass m,we get

T - mgsin30=ma

For block of mass 2m,we get

2mg- 2T= 2ma

Where T=tension,a=acc.

Solving these 2 eqns,you get a= g/4 = 2.5m/s²

KAREENA

Blazing goIITian

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Posts: 421

5 Jun 2012 17:23:00 IST

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answer is g/3

Rohan Vora

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Joined: 7 Feb 2011

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5 Jun 2012 17:47:06 IST

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Let tension in lower string be 2T..The acc. of mass 2m be a₂..And that of m be a₁..

By constraints, a₁=2a₂ (If you don't know about this,look http://www.goiit.com/posts/list/mechanics-constraint-equations-36922.htm)

So now,

2mg-2T=2ma₂ or mg-T=ma₂.......(1)

Also T-mgsin30=ma₁....(2)

(1)+(2) => g/2=a₂+a₁

But a₂=a₁/2

So g/2=3a₁/2

or a₁=g/3...Hit like if it helped..

Aman Sharma

Cool goIITian

Joined: 29 May 2012

Posts: 37

5 Jun 2012 17:49:52 IST

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Yeah..first eqn. is

T - mgsin30 = 2ma

KAREENA

Blazing goIITian

Joined: 19 Mar 2012

Posts: 421

5 Jun 2012 17:55:06 IST

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THANKS ROHAN AND AMAN

KAREENA

Blazing goIITian

Joined: 19 Mar 2012

Posts: 421

5 Jun 2012 18:07:22 IST

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@ROHAN THANKS A LOT ........EARLIER I WAS VERY CONFUSED ABOUT HOw TO SOLVE THESE TYPE OF QUESTIONS BUT AFTER SEEING (http://www.goiit.com/posts/list/mechanics-constraint-equations-36922.htm)all my doubts are cleared...........

Rohan Vora

Hot goIITian

Joined: 7 Feb 2011

Posts: 140

5 Jun 2012 18:14:43 IST

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Your welcome :)

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