Conservation of linear momentum

AI Thread Summary
In a collision between two cars moving toward each other, the principle of conservation of linear momentum applies, stating that the total momentum before the collision equals the total momentum after. The confusion arises regarding the common speed of the cars post-collision, which occurs in perfectly inelastic collisions where they stick together, resulting in a combined mass. The equation m1*v1 + m2*v2 = (m1 + m2)v12 is specifically for such scenarios. If the cars bounce off each other, a different approach is needed, as they do not share a common speed. Understanding the type of collision is crucial for applying the correct equations.
jahlin
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Homework Statement



Two cars 1 and 2 moving against each other collides.There are no external forces acting on them.

Homework Equations



conservation of linear momentum:
m1*v1+m2*v2 =(m1+m2)v12


The Attempt at a Solution


I have solved the problem but my question is how come they have a common speed after the collision?I don't understand this part can someone clarify it please.
 
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The equation you wrote is the one used when the two objects stick together when they collide, so after the collision there is only one object with a mass of m1+m2. This is called a perfectly inelastic collision. You can't use that equation if the objects bounce off each other.
 
thanks a bunch mikelepore!
 

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