question: Dry-firing a bow is bad because with no arrow the "energy" has nowhere to go. Mathematically it makes perfect sense but what is physically happening to the materials to cause this?
comment: The Energy goes someplace, it's just not the right place. The bow designer designs the bow to put the energy into the arrow. With no arrow, the energy goes into the string. This moves the string too fast and too far. Then it "rings" back and forth too many times. All these excess motions eventually allow the energy that should have gone into the arrow to go into heat in the air around the bow. The downside is that the excess motion causes excess wear.
passages: Dry firing in archery, also known as "dry loosing", refers to the releasing of a drawn bow without an arrow. This practice should be avoided as much as possible, because without the mass of the arrow to absorb the elastic energy released, the energy is instead dissipated through vibration of the bowstring and the bow limbs, and can do significant structural damage to the bow itself. Compound bows are particularly susceptible to damage due to high tension and numerous moving parts. Dry firing a modern high-poundage compound bow even once may cause a combination of cracked limbs, bent axles, string derailment, cam warpage, string/cable failure, cable slide failure, and can even cause the bow to shatter. While some bows can survive a dry fire with no apparent damage, typically manufacturers do not warrant their bows for dry firing, and any bow that has been dry fired needs to be thoroughly inspected for damage before shooting again. In particular, the limbs need to be inspected for cracking around cam axles and the opening of the slot where the cams or pulleys fit in (since they tend to tilt sideways during a dry fire).
   Even with a release aid mechanism some of this effect is usually experienced, since the string always accelerates faster than the retaining part of the mechanism. This makes the arrow oscillate in flight—its center flexing to one side and then the other repeatedly, gradually reducing as the arrow's flight proceeds. This is clearly visible in high-speed photography of arrows at discharge. A direct effect of these energy transfers can clearly be seen when dry firing. Dry firing refers to releasing the bowstring without a nocked arrow. Because there is no arrow to receive the stored potential energy, almost all the energy stays in the bow. Some have suggested that dry firing may cause physical damage to the bow, such as cracks and fractures—and because most bows are not specifically made to handle the high amounts of energy dry firing produces, should never be done.
   Crossbows, with their high draw weights, are even more likely to be damaged by dry firing.
  
  Section::::Etymology.
  
  The term dry firing is most likely derived from the similar phrase "dry run (testing)", which is a rehearsal or testing process and in the case of the firearm, one is "testing" the trigger action and observing the hammer or striker drop, without using live ammunition. Sources indicate that "dry" originates from exhibitions by late-19th-century fire departments in the United States, where drills (runs) were conducted for public viewing without the use of water (dry).
  
  Section::::See also.
  
  BULLET::::- Gun safety
  
  BULLET::::- Hang fire
   For safety reasons, a bow should never be shot without an arrow nocked; without an arrow, the energy that is normally transferred into the projectile is instead directed back into the bow itself, which will cause damage to the bow's limbs.
  
  Section::::Construction.:Arrowheads.
   Traditional materials include linen, hemp, other vegetable fibers, sinew, silk, and rawhide. Almost any fiber may be used in emergency. Natural fibers would be very unusual on a modern recurve bow or compound bow, but are still effective and still used on traditional wooden or composite bows. Sinew and hide strings may be seriously affected by water.
  
  Widely used modern materials are stronger for their weight than any natural material, and most are unaffected by water. They include:
   Dry fire
  
  Dry firing is the practice of "firing" a firearm without ammunition or practicing the manipulation of a firearm with an inert training platform such as a SIRT, Laserlyte, or LaserAmmo training firearm. If done incorrectly, dry firing may be mechanically damaging to some firearms – especially rimfire weapons, where the firing pin in most designs will impact the breech face if the weapon is dry-fired. Because of this, precautions (such as the use of snap caps) need to be taken if such a weapon is to be deliberately dry-fired.
  
  Section::::Benefits.
   The first advantage of using a release aid is the drastic decrease in chance of dry firing a compound bow. Doing this runs the risk of damaging the bow, and can result in the injury of the user.
   It is generally acceptable to dry fire more modern centerfire firearms without a cartridge or snap cap for limited volume training. Older designs such as the CZ 52 and Colt Single Action Army are exceptions. However, dry firing a rimfire firearm, striker based firearms or guns with angled firing pins (such as revolvers with hammer-mounted firing pins or older shotguns) can damage the gun. Furthermore, damage can occur to the chamber mouth of a rimfire firearm. Ultimately, one should check with the manufacturer of the gun to ascertain if it is safe to dry fire, but you should use a snap cap for all high volume dry fire training where the firing pin articulates.
   Flexing of the arrow when shot from a modern 'centre shot' bow is still present and is caused by a variety of factors, mainly the way the string is deflected from the fingers as the arrow is released.
   Another important consideration is that the IBO (International Bowhunter Organization) recommends at least 5 grains of total arrow weight per pound of draw weight as a safety buffer. This means a bow that draws 60 lb would need at least a 300 grain finished-with-tip arrow. Shooting arrows lighter than this guideline risks damage to the bow similar to that caused by dry-firing, which can in turn cause injury to the archer or anyone standing nearby. Shooting arrows that are too light also voids most manufacturer warranties.
  
  Section::::See also.
  
  BULLET::::- Bow shape
  
  BULLET::::- Bow (weapon)
  
  BULLET::::- Binary cam
  
  BULLET::::- Crossbow
   Less powerful bows require arrows with less dynamic spine. (Spine is the stiffness of the arrow.) Less powerful bows have less effect in deforming the arrow as it is accelerated (see "Euler" buckling, case I) from the bow and the arrow must be "easier" to flex around the riser of the bow before settling to its path. Conversely, powerful bows need stiffer arrows with more spine, as the bow will have a much greater bending effect on the arrow as it is accelerated. An arrow with too much dynamic spine for the bow will not flex and as the string comes closer to the bow stave, the arrow will be forced off to the side. Too little dynamic spine will result in the arrow deforming too much and being propelled off to the other side of the target. In extreme cases, the arrow may break before it can accelerate, which can be a safety hazard.
   Section::::In archery.
   This capital cost is made up of two parts. First, there is the replacement cost of substituting the arrow when it is lost in production. This is formula_22, or the competitive price of the arrows, multiplied by the proportion formula_23 of arrows lost after each shot. Second, there is the net rental or return required by the arrows' owner (who may or may not be the same person as the hunter using it). This can be expressed as the product formula_24, where formula_25 is the (uniform) "net rate of return" of the system.
   As a twin cam system relies on each cam rotating independently, based solely on the force of the string and the resistance of the bow limbs being absolutely symmetrical, there is room for a twin cam system to "lose tune" through wear and tear, string stretch, or just general age. The effect of a detuned twin cam bow is that the two cams rotate out of sync with each other, causing the bowstring to accelerate in two alternating directions upon release. This causes a number of adverse consequences, the most obvious being unsteady arrow flight.
   Electrical seasoning involves running an electric current through the lumber causing heat to build up drying the wood. This method is expensive but is fast and uniform quality.
  
  Section::::Drying defects.
  
  Drying defects are the most common form of degrade in timber, next to natural problems such as knots (Desch and Dinwoodie, 1996).
  
  There are two types of drying defects, although some defects involve both causes:
  
  BULLET::::1. Defects from shrinkage anisotropy, resulting in warping: cupping, bowing, twisting, crooking, spring and diamonding.
   Many bows, especially traditional self bows, are made approximately straight in side-view profile. They are generally referred to as straight, despite the minor curves of natural wood and the "set" or curvature that a wooden bow takes after use. When the archer commences the draw, mechanical advantage is at its greatest and the bow limbs are only pre-stressed to the strung position; therefore drawing weight is at a minimum. However, the drawing weight rapidly increases because mechanical advantage reduces (consider the string is pulling more and more directly on the limbs) and stresses are building up in the limbs. Consequently, drawing weight 'stacks' (very rapidly increases). On release, the reverse happens, the arrow is accelerated by maximum force, and this force rapidly decreases. Hence, the arrow must be sturdy enough to withstand such acceleration and, as the string may decelerate, it is possible for the arrow to leave the string prematurely, which is inefficient.
   More technically, the free electron model gives a basic description of electron flow in metals.
  
  Wood is widely regarded as an extremely good insulator, but its resistivity is sensitively dependent on moisture content, with damp wood being a factor of at least worse insulator than oven-dry. In any case, a sufficiently high voltage – such as that in lightning strikes or some high-tension power lines – can lead to insulation breakdown and electrocution risk even with apparently dry wood.
  
  Section::::Temperature dependence.
  
  Section::::Temperature dependence.:Linear approximation.
   There are three primary symptoms of target panic. An archer suffering from target panic may experience a premature anchor, where the bow appears to become very heavy and it is difficult for the shooter to come to a full anchor position. A second symptom is referred to as a premature hold, where an archer "locks up" or "hits a wall" that they are unable to move past as they try to align their arrow with the target. The third symptom is referred to as a premature release and is characterized by an inability to come to full anchor without releasing the arrow.
   Shooting errors
  
  In firearm or airsoft shooting, shooting errors or shooting mistakes are shooter's actions or external influences, leading to the consequence that a bullet or pellet misses the spot the shooter intended to hit. Shooting errors can be classified as shooter faults such as aiming errors and triggering errors, and errors caused by external influences.
   Yi Seonggye, the founding king of Joseon was known to have been a master archer. In a battle against Japanese pirates, Seonggye, assisted by Yi Bangsil, killed the young samurai commander "Agibaldo" with two successive arrows, one arrow knocking out his helmet, with the second arrow entering his mouth. In his letter to General Choi Young, Seonggye lists as one of five reasons not to invade Ming China as during the monsoon season, glue holding together the composite bow weakens, reducing the effectiveness of the bow.
   Archer's paradox
  
  The archer's paradox is the phenomenon of an arrow traveling in the direction it is pointed at full draw, when it seems that the arrow would have to pass through the starting position it was in before being drawn, where it was pointed to the side of the target.
  
  The bending of the arrow when released is the explanation for why the paradox occurs and should not be confused with the paradox itself.
   The efficiency of bows also varies. Normally between 70-85% of the stored energy is transferred to the arrow. This stored energy is referred to as potential energy. When transferred to the arrow it is referred to as kinetic energy. The product of S.E./P.D.F. and efficiency can be called the power factor. There are two measurement standards of this quantity - AMO and IBO speed. AMO is defined as the initial velocity of a 35 g / 540 grain arrow when shot from a bow with a peak draw weight of 270 N / 60 lbf and draw length 76 cm / 30 inches. IBO speed is defined as the initial velocity of a 22.7 g / 350 grain arrow shot from a bow with a peak draw weight of 300 N / 70 lbf and a draw length of 76 cm / 30 inches.
   Recurved limbs also put greater strain on the materials used to make the bow, and they may make more noise with the shot. Extreme recurves make the bow unstable when being strung. An unstrung recurve bow can have a confusing shape and many Native American weapons, when separated from their original owners and cultures, were incorrectly strung backwards and destroyed when attempts were made to shoot them.
  
  The unqualified phrase "recurve bow" or just "a recurve" in modern archery circles usually refers to a typical modern recurve bow, as used by archers in the Olympics and many other competitive events.
   Modern arrows are made to a specified 'spine', or stiffness rating, to maintain matched flexing and hence accuracy of aim. This flexing can be a desirable feature, since, when the spine of the shaft is matched to the acceleration of the bow(string), the arrow bends or flexes around the bow and any arrow-rest, and consequently the arrow, and fletchings, have an un-impeded flight. This feature is known as the archer's paradox. It maintains accuracy, for if part of the arrow struck a glancing blow on discharge, some inconsistency would be present, and the excellent accuracy of modern equipment would not be achieved.
   The materials must withstand these stresses, store the energy, and rapidly give back that energy efficiently. The amount of energy stored is determined by the stresses withstood and the shape of the limb, from the unstrung position to strung (consider as pre-stressed), then de-formed further to full draw as the recurve unwinds. These basic principles of changing mechanical advantage, to efficiently store more energy, and deliver it to accelerate the arrow, were clearly understood in antiquity, as shown by the examples that follow.
  
  Section::::Straight bows.
  
presuppositions: Energy has nowhere to go when a bow is dry-fired.
corrections: Energy does go into the string and eventually into the heat of the air around the bow. 
raw_presuppositions: Energy has nowhere to go when a bow is dry-fired. Energy has nowhere to go when a bow is dry-fired.
raw_corrections: Energy does go into the string and eventually into the heat of the air around the bow.  Energy does go somewhere when a bow is dry-fired, but into the wrong place.