First of all, I want to apologize for my English I'll try to explain my self clearly. I want to share one question about Newtonian mechanics from my homework, of which I can't understand the logic behind it.
As you can see in the picture, a body of mass $m = 1$ kg moves straight along the x-axis, with a velocity of $v_i = 20$ m/s. Another object with mass $M = 10$ kg is resting without friction.
- What is the maximal height that mass $m$ will rise (considering gravitational force), after the collision between two masses?
In the exercise it is stated that $mv=MU$ on the x-axis and the collision is absolutely elastic (by conservation of momentum law).
Now my question is how is it possible that mass $m$ still has velocity on y-axis when all the momentum after the collision moved to mass $M$?