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# The Physics Behind Throwing a Lacrosse Ball

by
Matthew Larson
I have completed the first two years of medical school, during which time I have developed expertise in writing on medical and science topics for eHow and Livestrong. My blog, cAMPScience.org, has recently been approved at DMS for "Blogger" status, which will allow me to continue to develop my brand with this organization. I will provide high quality articles, using only the best sources in medical and science research.
Throwing a lacrosse ball demonstrates Newton's three laws of motion. Photo Credit: Peter Dean/iStock/Getty Images

Throwing a lacrosse ball demonstrates several important properties of physics. An understanding of these laws may help as you excel in the sport. However, beyond understanding the precise physics of the game, practice remains the best way to become proficient and develop your own style of passing.

## Newton's First Law: Inertia

An object at rest will remain at rest until acted up by an external force. In the case of lacrosse, the net cradles the ball, which connects to the stick before a player finally acts upon it. A centripetal force exists on the ball as the player throws it; the ball’s friction against the net keeps the ball in the pocket while the stick accelerates around. Once the ball gets released, it will continue in a straight line until acted upon by an outside force such as another player’s stick, or simply the force of gravity as the ball falls to the ground.

## Newton's Second Law

You may calculate the force of a player’s throw using Newton’s second law: Force equals mass times acceleration. The acceleration applied to the ball during the throw directly determines the force of the pass, because the mass remains constant.

## Newton's Third Law

For every action there exists an equal and opposite reaction. When throwing a lacrosse ball, the stretch in the netted pocket and the motion of the ball counteracts the force put into swinging the stick. The ball gets forced forward as a reaction to the work applied to the stick.

## Torque and Lever Arm

When carefully examining the physics of a lacrosse pass, the lever arm created proves important for building the appropriate throwing motion. In order to throw the ball from the netted pocket, pull the stick backward with the bottom hand and push it forward with the upper hand. This motion creates a lever arm that will direct the ball forward with the centripetal force you have created with the stick. By pivoting the stick through your upper hand, creating force in both the upper and lower hands, you generate large torque forces and throw the ball great distances.

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