Momentum is conserved period.
total kinetic energy conserved? No, where did you get that idea?
Think about a bullet hitting a block and getting embedded. I am sure you have done that for homework. You solve it using conservation of momentum. However
(1/2)m V^2 of bullet
is not equal to
(1/2)(m + M) v^2 of bullet and block after
during the penetration, mechanical energy escaped as heat.
Does the total kinetic energy of an isolated system necessarily have to be conserved when its total momentum is conserved?
2 answers
Thank for the explanation, I knew about momentum but the fact that kinetic energy was mentioned in the question just threw me off.