# 05 Physics of sports by wanghonghx

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```									Jessica Drobnick

Mike Stehlin

The Physics Behind Sports

The act of hitting or throwing a ball is extremely common in many of the modern sports we have

today. Sports like golf and football, for example, require an athlete to impose a force onto a ball in

order to reach a desired location. The laws of projectile motion are prevalent in these sports where

there is horizontal and vertical motion occurring at the same time to an object.

Projectile motion involves an object traveling in vertical and horizontal motion simultaneously.

In the vertical sense, the force of gravity dictates a constant acceleration and will determine velocity

changes, both in magnitude and direction (http://cnx.org/content/m13837/latest/). Using the angle at

which the object is projected, one can break the velocity of the object into its vertical and horizontal

components. From those vectors, one can determine both the maximum height the object reaches, the

time the object is in the air, and how far the object will travel.

In football, it is the quarterback’s job to throw the football to a receiver downfield. In order to

successfully do this, the quarterback must know the right angle and speed at which to throw the ball to

get it to its desired location. It is rare for the quarterback to throw the ball to a stationary target, most of

the time they must anticipate where the receiver will be and make sure that the ball arrives there at the

same time. When he wants to lead the receiver, the quarterback will want to throw the ball at a greater

angle to the horizontal in order to give the receiver more time to get to the ball. When the quarterback

does not want to lead the receiver as much, but wants to throw the ball the same distance, he must

throw it at a lesser angle to the horizontal. This illustrates the understanding of angles and their effect

on distance traveled and time spent in the air. Balls thrown at complementary angles at the same
velocity, ignoring air resistance, will travel the same distance. The larger angle will take a longer time to

reach the end point.

Similar to football, golf utilizes the same principles of projectile motion. Although in golf the

target of the ball is stationary, the athlete still depends on angles and velocity to direct the ball to the

appropriate spot. Angles are especially important to a golfer. For example, when a golfer must hit a ball

over tall obstacles, like trees, he must strike the ball at a specific velocity and launch it at a precise angle.

If the ball is hit at too low of an angle it won’t clear the trees, and if it is hit at too high of an angle and

with too much initial velocity, it could go over the green entirely.

This information allows us to understand the physics behind the sports we love. Furthermore, it

allows us to appreciate and recognize the physics principles that athletes utilize regularly and

instinctively. Also, understanding these aspects of projectile motion can help anyone play these sports

more successfully.

Works Cited

Connexions - Sharing Knowledge and Building Communities. Web. 20 Apr. 2010. <http://cnx.org>.

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