What happens to a wave as it hits a surface it cannot pass through?
When a wave hits a surface that it cannot pass through, it bounces off in a reflected angle. As shown in the ball experiment, when the ball hit the wall at a slight angle, it bounced off to the exact opposite angle: / to \. If it is hit at the wall in a deeper angle, it also comes off in a deeper angle of reflection.
Does energy (density of the ball) affect the wave's path?
Yes, it does. Monica and I took two same-sized marbles to test this. One of them was heavier, or denser, than the other because the other one was plastic. The denser marble always came back at a deeper angle, whether we rolled it that way or not because the force of it was stronger, the pull.
How is the angle at which the ball (wave) hits the wall related to the angle at which it bounces back?
As mentioned before, the deeper the angle that the ball was rolled, the deeper the angle that the ball comes back on. This is called the reflective angle, or the reflection. This was also the angle of incidence.