Shooting a puck, wrist or slap shot, requires a player, using their stick to apply a force greater than the frictional forces(very little, due to ice being relatively smooth) resisting the puck's movement. Players have the ability to generate lift because all stick blades have a certain "tilt" angle.(the face of the blade is turned slightly upwards). During the shot, the puck slides along the face of the blade and it is the tilt which allows it to be lifted off the ice surface. Players who generate high speed velocity of their slap shot, has a large force and time of impact of the blade and hockey puck. Players wind up for a slap shot, to generate a large force and then hit the hockey puck in a certain time. Force * time = impulse = change of mass * velocity. Therefore a large impulse equals a pretty large velocity. Players who attempt wrist shots, have a less wind up because they want more accuracy then power. The less force the player has on the hockey puck from the blade of the stick, means less impulse. Therefore a lower velocity of the hockey puck relative to the hockey puck hit by a slap shot.