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25 Dec 2007 18:47:29 IST
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Momentum conservation is applied only when conservative forces are there
or it can be applied to any system???
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IMPOSSIBLES ARE OFTEN UNTRIED... |
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i dont think momentum is conserved over the whole period of collision in the presence of non conservative forces. when two bodies collide on a rough table, is momentum conserved?? maybe not over the whole period of collision. but at the instant of contact, momentum is conserved
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25 Dec 2007 19:18:24 IST
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but we during collision we take the momentum of bodies after and before collision
not at the time of collision ....??????
also Why we donot apply conservation of energy in those sort of problems??
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25 Dec 2007 19:26:20 IST
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abey yaar by - 'instant of collision' i mean that the time period between before and after collision is so small, that the non-conservative force acting on it can be said to have little or negligible effect on it you can use work energy theorem that involves total work done, by both conservative forces and non conservative forces. specifically, total work done by non-conservative forces = total change in energy (usually mechanical) = E2 - E1
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Ratings do not necessarily signify that someone is good, or bad. I'm here to learn and help others learn, and a person unlocking the mysteries with the help of my solution, to a nagging problem, means more pleasure to me than ratings can ever make me feel. |
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25 Dec 2007 23:38:52 IST
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Re-read the basic rule of momentum conservation.
It says, WHEN NO EXTERNAL FORCES are acting ....................
So you see. you can use conservation of momentum only when no ext. forces are acting. In case of collision, you consider both the colliding bodies as the system, as a result, you have no external force and hence you can apply momentum conservation.
Remember : momentum is not conserved at the instant of collision. ( as Indzee said)
PS : rate me if you find it helpful
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27 Dec 2007 23:43:50 IST
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conservation of linear & angular momentum is only applicable when external force & torque is 0 respectively
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27 Dec 2007 23:48:22 IST
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ya no external force should be acting on the system
if it is, then the resultant of the force should be taken on both sides
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27 Dec 2007 23:52:21 IST
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Momentum is conserved when net external force is 0,it has nothing to do with conservative or non conservative forces,but energy is only conserved when conservative forces act on a system
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AIR 2515 IIT JEE 2010
IIT Hyderabad Electrical Branch |
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9 Mar 2009 08:28:22 IST
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F = dP/dt ... if F=0 then there is no change in momentum... It is very very essential to decide your system... now try to make its FBD and if net resultant external forces are zero then you can conserve momentum
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