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Newton’s First Law of Motion states that an object in motion tends to stay in motion unless acted on by an external force. Without friction, velocity would be constant after the first push-off and the skater would glide until he or she crashes into the boards. Though that is an effective way to stop, increasing friction is a much safer way to decrease velocity and stop as needed. Have We Mentioned Friction? Friction is again the answer when the question arises as to why hockey players are careful to make sure their skates are always sharp. A sharp skate blade has less surface area than one that is dull. This means less contact with the ice surface, and therefore less friction, allowing the skates to glide more easily going forward or backward. What happens when the skater wants to change direction quickly or suddenly? Sharp blades also help in the opposite way as well. Sharper blades cut deeper into the ice when planted, which provides the resistance that

allows skaters to stop the momentum in one direction and apply the force necessary to move in a different direction. More Than Just Force Of course, there is more to skating than applying force with the hips and legs to move in a given direction.

Hockey players can change direction suddenly by digging their blades into the ice and applying force to push off in the direction they want to go.

14 CONNECTING STEM AND SPORTS | ICE HOCKEY