I'm not being extremely exact here, but suppose there's a puck in a board where there's very little friction. Both puck and board are at rest. Suppose the board starts from rest to some decent speed, so there's definitely this acceleration, by virtue of which (and also less friction), puck slides backward if that board is moving forward or in other words (pucks) remains at same place by virtue of inertia. And after a few seconds when the board reaches a decent speed, it keeps at it. Thereby, it becomes again an inertial frame. Now what happens to the puck now when the board reaches constant pace? 1. Will it too acquire that speed? 2. Will it fall off the board as it keeps travelling backwards (as board moves forward)? Here friction is bare minimum and has a very minuscule effect. Board is long enough to have puck on it for whatever backward slide it faces. Obviously, when there's sufficient friction, it acquires the same speed as the board, but what happens when the friction is sufficiently less or bare minimum?