Block 1, with mass m1 and speed 4.5 m/s, slides along an x axis on a frictionless floor and then undergoes a one-dimensional elastic collision with stationary block 2, with mass m2 = 0.41m1. The two blocks then slide into a region where the coefficient of kinetic friction is 0.45; there they stop. How far into that region do (a) block 1 and (b) block 2 slide?

If you could help with this I would be soo happy! Everything I get turns out wrong, and i'm running out of ideas.

4 answers

You seem to have omitted the mass m1. It cannot be solved without that information.
That's all the information that I'm given.
The masses usually cancel out of equations, so I'm just guessing that that's what happens here. I just don't know how to start it.
You solve for the final velocities of the blocks with two equations in two unknowns: conservation of momentum and conservation of energy. The unknown m1 will cancel out of the solutions. Calculating the distance they travel against friction will likewise cancel out m1.