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vissh
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Hello :)
<Q>A wheel of moment of inertia "I" and radius "R" is free to rotate about its center as shown in figure http://s1102.photobucket.com/albums/g448/vissh/?action=view¤t=pulley-1.jpg" .A string is wrapped over its rim and a block of mass m is attached to the free end of the string. The system is released from rest. Find the speed of the block as it descends through a height h.
>K.e.of a body rotating abt an axis with M.O.I = I and angular velocity 'w' = (Iw2)/2
>Principle of conservation of energy [applied when work done by external forces is 0 and the internal forces are conservative]
>Conservative forces are those forces whose work done only depend on initial and final position only.
>I was able to solve the problem[using a different way shown below]
>The book got a solution which i can't understand :-
It said (let at that instant) velocity of block is "v" and thus, its k.e. is (mv2)/2. Thus, angular speed of the pulley is "v/r" and thus its K.E. is [I(v/r)2]/2 .
Using principle of conservation of energy :-
..... mgh = (mv2)/2 + [I(v/r)2]/2
>The problem is that I can't get How "tension" in string is considered to be conservative and if it is conservative, isn't a P.E. also be stored w.r.t. it .
Homework Statement
<Q>A wheel of moment of inertia "I" and radius "R" is free to rotate about its center as shown in figure http://s1102.photobucket.com/albums/g448/vissh/?action=view¤t=pulley-1.jpg" .A string is wrapped over its rim and a block of mass m is attached to the free end of the string. The system is released from rest. Find the speed of the block as it descends through a height h.
Homework Equations
>K.e.of a body rotating abt an axis with M.O.I = I and angular velocity 'w' = (Iw2)/2
>Principle of conservation of energy [applied when work done by external forces is 0 and the internal forces are conservative]
>Conservative forces are those forces whose work done only depend on initial and final position only.
The Attempt at a Solution
>I was able to solve the problem[using a different way shown below]
>The book got a solution which i can't understand :-
It said (let at that instant) velocity of block is "v" and thus, its k.e. is (mv2)/2. Thus, angular speed of the pulley is "v/r" and thus its K.E. is [I(v/r)2]/2 .
Using principle of conservation of energy :-
..... mgh = (mv2)/2 + [I(v/r)2]/2
>The problem is that I can't get How "tension" in string is considered to be conservative and if it is conservative, isn't a P.E. also be stored w.r.t. it .
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