Difference between revisions of "Conservation of momentum"

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imported>Milton Beychok
m (Conservation of Momentum moved to Conservation of momentum: To change M to m in "momentum")
imported>Mark Widmer
(Added remarks about external forces.)
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'''Momentum is always conserved.'''  The momenta of individual objects in a system may vary, but the vector sum of all the momenta will not change.  Therefore, momentum is said to be conserved.
'''Momentum is always conserved.'''  The momenta of individual objects in a system may vary, but, in the absence of any external forces, the vector sum of all the momenta will not change.  Therefore, momentum is said to be conserved.
 
If an external force -- that is, a force exerted by an object outside the system -- is exerted on any objects within the system, then the total momentum will change.


The conservation of momentum in a glancing collision between two objects is expressed as <math> \left(M_\mathrm{1}V_\mathrm{1i}\right) + \left(M_\mathrm{2}V_\mathrm{2i}\right) = \left(M_\mathrm{1}V_\mathrm{1f}\right) + \left(M_\mathrm{2}V_\mathrm{2f}\right)</math>
The conservation of momentum in a glancing collision between two objects is expressed as <math> \left(M_\mathrm{1}V_\mathrm{1i}\right) + \left(M_\mathrm{2}V_\mathrm{2i}\right) = \left(M_\mathrm{1}V_\mathrm{1f}\right) + \left(M_\mathrm{2}V_\mathrm{2f}\right)</math>


The conservation of momentum in a collision between two objects where the two objects become one is expressed as <math> \left(M_\mathrm{1}V_\mathrm{1i}\right) + \left(M_\mathrm{2}V_\mathrm{2i}\right) = \left(M_\mathrm{1} + M_\mathrm{2}\right)V_\mathrm{f}</math>
The conservation of momentum in a collision between two objects where the two objects become one is expressed as <math> \left(M_\mathrm{1}V_\mathrm{1i}\right) + \left(M_\mathrm{2}V_\mathrm{2i}\right) = \left(M_\mathrm{1} + M_\mathrm{2}\right)V_\mathrm{f}</math>

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Momentum is always conserved. The momenta of individual objects in a system may vary, but, in the absence of any external forces, the vector sum of all the momenta will not change. Therefore, momentum is said to be conserved.

If an external force -- that is, a force exerted by an object outside the system -- is exerted on any objects within the system, then the total momentum will change.

The conservation of momentum in a glancing collision between two objects is expressed as

The conservation of momentum in a collision between two objects where the two objects become one is expressed as