The Physics of Archery

The Physics of Archery

When an archer is in the yard with his or her bow in the archers’ and their arrow knocked, the archer stares at the target; all he or she archer is thinking about is one of the components of archery, arrow flight (Kyle, 1998). Then when the archer takes their bow in the house for fine tuning, whether it is owners’ sight or bow, they are performing another component of the physics of archery, bow mechanics (Kyle, 1998). The sport of archery uses laws of physics in the area of bow mechanics and arrow flight (Kyle, 1998). These components are very important to the physics of archery because they display proper techniques that archer is required to excel in, the sport of archery (Kyle, 1998).

Bow mechanics, is a component because it plays a major role in the physics of archery (Kyle, 1998). Bow mechanics is made up of many parts, draw weight, draw length, types of bows, bow limb, and the bow materials are all sub components of bow mechanics (The Bow, 2008). Draw weight is the first component of bow mechanics.

The draw weight is the weight that the archer feels on his or her fingers when he or she pulls back the bow (Kyle, 1998). The draw weight is important because the more the draw weight the faster the arrow will go (Kyle, 1998). When an archer first tries to pull back his or her bow the draw weight is felt (Kyle, 1998). The length where the archer is most is comfortable with is the draw weight (Tapley, 2000). The greater the draw length the more the draw weight (Tapley, 2000).

The bow limb acts like a spring for the bow (Tapley, 2000). As the string is pulled back the bow is used for a spring and this spring exerts the bows force (Tapley, 2000). The lighter the material that the bow is made of, the more the energy that is exerted from the bow to the arrow (Tapley, 2000). Thus the faster the arrow will go to the target.

There are many materials that are used to make bows: aluminum, fiberglass, and wood (Tapley, 2000). All of these are light materials. Although crossbows are made out of steel this cuts the transfer of energy down because it is so heavy (Tapley, 2000). Crossbows are used today primarily for target shooting and hunting (Tapley, 2000).

There are many types of bows. Straight Bows are the main kind of bow (Tapley, 2000). There are two main straight bows which are, short bows and long bows. Short bows are small straight bows that store less energy (Tapley, 2000). The short bows arrow range is smaller than the long bow’s, the short bow’s axle-to-axle length ranges for 32in-38in (Tapley, 2000).

Long Bows are the very opposite of the short bow, long bow’s axle-to-axle length ranges from 38in-45in (Tapley, 2000). The long bows larger size allows it to store and produce more energy to the arrow than the short bow (Tapley, 2000). The more work that is used to shoot a straight bow the more energy that has to be produced by the bow user (Tapley, 2000). There are many other types of bows: composite, compound, and recurve bow.

The composite bow is like a recurve bow and a compound bow combined (Gopan, 2008). It uses pulleys and levers to enhance the bows force and energy. Theses two materials work together to increase the amount of power that is exerted from the bow to the arrow (Gopan, 2008). This type of bow is used for sport also.

The compound bow has many uses such as hunting, and sport. The compound bow is used worldwide because of the energy transfer that the compound bow has to offer. Which means that the bow can shoot further distances and more accurate than composite and recurve bows. The compound bow uses levers and pulleys that enhance the power of the bow (Gopan, 2008).

The recurve bow uses the same law of physics as the straight bow, which are bow mechanics and arrow flight. The limbs are bent to a curve thus gives it its name. To shoot a recurve bow takes aiming skills. A recurve bow must be shot with the archer’s fingers. A recurve bow is mainly made out of wood and fiberglass, but can be made out of other materials as well (Gopan 2008). Since a recurve bow is made out of these materials the bow has less force exerted from the bow to the arrow (Gopan, 2008).

Q: “If archery is just human work, then why can't someone throw an arrow that fast and far?” (The Bow, 2008).

A: “For a number of reasons. One-- When you throw something; you're also throwing your arm's Mass along with it. Two-- Humans are only capable of exerting a certain amount of Force. With a bow, a human can exert that force over a longer period of time, storing it up in the force of Elastic Potential Energy” (The Bow, 2008).

Arrow flight is a vital role in the physics of archery. The most important part of archery is the actual flight of the arrow (Kooi, 1991). The goal of archery is get the arrow into flight (Kooi, 1991).

During the Battle of Agincourt, 6000 English archers defeated a French army of 30,000 knights and infantry (Kooi, 1991). This shows how perfect arrow flight and mark will always be an advantage (Gopan, 2008). The range of the arrow depends on the weight of the arrow, the amount of wind or friction applied to the arrow, and the air pressure against the arrow (Gopan, 2008). If the arrow has a heavy weight then the arrow will fly slow and not go far (Gopan, 2008). If the arrow has a light weight then the arrow will fly fast and have a further distance than a heavy arrow (Gopan, 2008).

A main goal of archery is to shoot arrows with the highest possible kinetic energy (Ugo, 2000). When an archer pulls back his or her bow, the energy that is used is converted into kinetic energy (Gopan, 208). The kinetic energy gives the arrow its power (Gopan). Short bows have little kinetic energy because it is so short (Gopan, 2008). Long bows are the opposite of the short bow, they store more kinetic energy because the longer the bow the more the kinetic energy (Gopan, 2008). Some short bows shoot faster than some long bows because the short bow has less mass than the long bow (Gopan, 2008).

The compound Bow has a higher kinetic energy because the compound bow uses pulleys to increase the bow’s power (Gopan, 2008). Since the compound bow has more power, the arrow will fly faster (Gopan, 2008). The faster the arrow, the less movement the sight will have. This is true because as the archer shoots from further distances the arrow will fly faster and less work has done to the sight (Gopan, 2008).

The recurve bow has little kinetic energy because it is a bow made out of wood, and many other materials. The archer can almost make a recurve bow out of anything (Gopan, 2008). A recurve bow was the first bow made in earlier times (Tapley, 2000). This bow was used sometimes for hunting and war (Kyle, 1998). The recurve and the long bow were used by the Native Americans and other countries for hunting and war (Kooi, 1991).

A larger bow can shoot a larger and heavier arrow (Ugo). In ancient times bow-like machines much larger than ordinary bows (catapults) were built and used to shoot very large arrows or projectiles (Ugo, 2008). Around 20,000 B.C., the bow had advanced to the point where sharpened flint arrowheads, tied with sinew to wooden shafts, were used for bow hunting (Gareth, 2000). There are two main types of points for arrows: broadheads and field points (Ugo, 2000). Field points are used for archery and broadheads are used for hunting (Ugo, 2000).

When air resistance is present, a drag force acts on the arrow to slow it down by transferring momentum from the arrow to the air (Gopan, 2008). Two types of drag forces act on an arrow during its flight: form drag and shear drag (Gopan, 2008). As the arrow flies through the air, it drags the adjacent air along (Gopan, 2008). This air drags the air around it as well creating layers of air with different velocities along the arrow this causes friction (Gopan, 2008).

The form drag is proportional to the square of the arrow’s velocity and can be described by the equation, F = c*u^2 (Gopan, 2008). In this equation, F is force. C is equal to the constant gravitational pull, which is 9.8 meters per second squared. U is the velocity of the arrow squared (Gopan, 2008). Constant and velocity are multiplied by each other. This would equal the form drag of the arrow.

The shear drag is proportional to the velocity of the air and can be described by the equation, F = c*u, where c is a constant and u is the velocity of the arrow (Gopan, 2008). As the arrow flies through the air, the shear drag creates eddies (ruffling of the air) behind it (Gopan, 2008). The eddies drop off the arrow to form a turbulent wake, resulting in form drag (Gopan, 2008). As the arrow flies faster, it creates a greater turbulence and thus, equals a greater form drag (Gopan, 2008).

There are three main arrow types used in archery, aluminum, which is very durable, light in weight, great precision, and high consistency (Gopan, 2008). Carbon is the most durable, lightest, greatest precision and highest consistency (Gopan, 2008). Fiberglass is durable, however, fiberglass are not common (Gopan, 2008). Wood is light, least expensive, and esthetically pleasing. Wood arrows have a tendency to warp and break (Gopan, 2008).

The plastic vanes or feathers on an arrow are referred to as fletching (Foster, 2008). The vanes or feathers help the arrow to fly strait and give it more speed (Foster, 2008). The plastic vanes on an arrow allow the projection of the arrow to be smooth. This will create a straighter and longer flight time.

Feather vanes make the release of the arrow more resistance than the smooth plastic vanes (Foster, 2008). The feathers that are used on the arrow will make the air resistance rigid. This will cause the arrow to reduce speed drastically and cause a lower flight time. If the feathers get wet the arrow will not fly straight do to the weight of the water on the feathers. Because of these disadvantages archer tend to use synthetic feather vanes (Foster, 2008).

The physic of archery plays a key role in how accurate the archer will be in hitting the desired target. If the archer understands how the physics work on the arrow and the bow, the archer will have an advantage and more likely to be successful in archery. The different type of material that the bow is constructed of has a great effect on how fast and how accurate the arrow will fly. Thought history different types of bows have been used for specific purposes. The evolution of archery will continue to improve as technology and the understanding of how physics affects archery.

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