The stationary refers to the piece who's movement is not being resolved presently, that piece may have had momentum before the contact occurred. A pawn that contacts an opponents piece while moving in the forward, non-capture, direction, acts as if it has contacted a piece of its own color. Pawns may make a capture move to start movement, but may only be stopped by contact with another piece, a player may not use his turn to stop a pawn that is moving diagonally. Pawns do not have a 2 space opening move. Pawn promotion occurs on the first and twelfth rows.
Knights are able make continuing moves.
When a knight moves, it can continue to make knight moves in the same direction. Each knight move must land on an open square or enemy piece, which ends the move. Momentum will move the knight the same number of knight moves on each turn until the knight is stopped. The speed for a knight is twice the number of knight moves made. There is no check or restriction on moving into check.