An ice skater at rest pushes against a sled at rest, causing both the skater and sled to move away from each other with different accelerations. This is an example best described by
According to Newton's third law of motion, for every action there is an equal; and opposite reaction.
According to this law, if an object Y exerts a force on another object X, then object X exerts a force that is equal in magnitude but opposite on object Y.
Therefore, in this case, the action is the push by the ice skater against a sled at rest then the reaction is both the skater and sled moving away from each other at different accelerations.
