Final answer:
A gliding ice hockey puck on frictionless ice continues to move at a constant speed due to Newton's first law of motion. Friction, which is minimal on ice, is what usually slows down a puck.
Step-by-step explanation:
The physics behind a gliding ice hockey puck involves Newton's first law of motion -- objects in motion tend to stay in motion unless acted upon by an external force. On frictionless ice, a puck that starts sliding will continue to move at a steady velocity because there is no opposing force to slow it down. Friction is the resistance that a surface or object encounters when moving over another, and in ice hockey, the slick, frozen surface provides very little resistance.
Now consider an air hockey table, where air is pushed through tiny holes to create a thin layer between the puck and the surface, simulating a frictionless environment. Here, the puck can glide across the table almost uninterrupted. Similarly, a real ice hockey puck, when propelled across a rink, will continue moving until acted upon by another force, such as the stick of a player, the walls of the rink, or the natural friction that still exists, albeit minimal, on the ice.
In the event of collisions, such as a puck striking another puck, Newton's third law comes into play; for every action, there is an equal and opposite reaction, which is observable in the changes in velocity and direction post-collision. Energy is conserved during elastic collisions, while some is transformed into thermal energy or sound during inelastic collisions.