I am trying to make this puck glide back and forth maintaining a constant velocity. However, when it hits a wall, it somehow gains velocity in the y direction, which does not make sense if two perfectly flat surfaces are hitting each other. Everything has 0 friction.
The solution I was working on was making an invisible and ceiling that physically would not let the puck go upwards. The problem with this is that it still bounces upwards ever so slightly and causes it to lose velocity.