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16 Mar 2010 13:42:28 IST

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why does an ordinary beam balance stays horizontal about the fulcrum?

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why does an ordinary beam balance stays horizontal about the fulcrum?

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Nimisha Radhakrishnan

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16 Mar 2010 13:51:09 IST

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It does so only when the fulcrum is kept at its centre of mass. The mass on both sides of the fulcrum will be the same. so there will not be any torque acting on it. So it will not topple.

snail

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16 Mar 2010 21:45:01 IST

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@Nimisha Radhakrishnan

If centre of mass is at fulcrum it is not necessary that beam should remain horizontal. If the beam is inclined, still the moment on both sides will be same. So there will be no net torque even in inclined psition.

I feel that the fulcrum should be slightly above the centre of mass so that any small inclination will raise the centre of mass causing imbalance. So due to gravity the COM will come to lowest stable point ie below the fulcrum. Thus beam will remain horizontal always if masses on both the pans are equal.

paul

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24 Mar 2010 15:01:48 IST

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Dear Nimisha ,

if u apply a bit of geometry,you will see that com will not change its position in any case.whether it is at the fulcrum or below it.so there is no question of imbalance at any inclined position of beam due to motion of com.

edison

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22 Jun 2011 18:23:40 IST

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As the moments at that point are equal and is therefore a state of equilibrium.

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