Since there is friction, even though momentum is conserved, kinetic energies will not be conserved due to collision.=======================================…-Equal only right at the collision point.After that, a force from outside the system (of 2 cars),......
Times of forces acting are the same.
[m1v1 – m1u1] = [m2v2 – m2u2]
Change in momentum of carB = change in momentum of car A.
If there was no friction, then the kinetic energies will also be conserved.
Since there is friction, even though momentum is conserved, kinetic energies will not be conserved due to collision.
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Equal only right at the collision point.
After that, a force from outside the system (of 2 cars), provided by the friction of the roadway, causes the momentum relative to the earth to appear to disappear.
However, if the system is considered to be 2 cars + the earth, the earth actually speeds up a bit from the frictional force being applied to it. In the expanded system, therefore, momentum is always conserved.
