Projectile Motion
After the a shot is fired off a player's stick, the puck travels through the air with parabolic projectile motion. The puck will also continue its flight into the net or into the hands of the goalie. Most of the time the puck is fired at such a high velocity that spectators cannot see the puck's entire trajectory. This is why the glass in an arena needs to be built pretty high for safety reasons; a flying puck will continue along its path until it loses its vertical velocity due to gravity, or until it impacts something such as the glass. This is an example of Newton's first law. The diagram on the left is an example of what might happen when a shot misses its target. (See sheet of paper for calculations)
Below we examine the physics behind Sidney Crosby's goal:If Crosby skated at 5 meters/second (initial velocity), then the puck on his stick would be travelling at the same velocity. Suppose Crosby launched the puck with 10N of force. We can determine:
If Crosby was standing still and shot the puck with 10N of force, there would be no initial velocity. Therefore the puck's final velocity would only be 9 m/s. (14 m/s - 5m/s)
(Complete calculations found on sheet)
- The puck's acceleration towards the net - 87 m/s
- The puck's final velocity - 14 m/s
- Work done by stick - 1 J
- Change in energy [E(total)2 - E(total)1] - 11.6 J
- Power generated from the shot - 116 W
If Crosby was standing still and shot the puck with 10N of force, there would be no initial velocity. Therefore the puck's final velocity would only be 9 m/s. (14 m/s - 5m/s)
(Complete calculations found on sheet)