Projectile

A projectile being fired from anartillerypiece

Aprojectileis an object that is propelled by the application of an externalforceand then moves freely under the influence ofgravityandair resistance.Although any objects inmotionthrough space are projectiles, they are commonly found inwarfareandsports(for example, a thrownbaseball,kickedfootball,firedbullet,shotarrow,stone released fromcatapult).

Inballisticsmathematicalequations of motionare used to analyze projectiletrajectoriesthrough launch,flight,andimpact.

Motive force

See also:Projectile motion

Projectile and cartridge case for the hugeWorld War IISchwerer Gustavartillery piece. Most projectile weapons use the compression or expansion of gases as their motive force.

Blowgunsandpneumatic riflesuse compressed gases, while most othergunsandcannonsutilize expanding gases liberated by sudden chemical reactions bypropellantslikesmokeless powder.Light-gas gunsuse a combination of these mechanisms.

Railgunsutilize electromagnetic fields to provide a constant acceleration along the entire length of the device, greatly increasing themuzzle velocity.

Some projectiles providepropulsionduring flight by means of arocket engineorjet engine.In military terminology, arocketis unguided, while amissileisguided.Note the two meanings of "rocket" (weapon and engine): anICBMis a guided missile with a rocket engine.

An explosion, whether or not by a weapon, causes the debris to act as multiple high velocity projectiles. An explosive weapon or device may also be designed to produce many high velocity projectiles by the break-up of its casing; these are correctly termedfragments.

In sports

Ball speeds of 105 miles per hour (169 km/h) have been recorded inbaseball.

In projectile motion the most important force applied to the ‘projectile’ is the propelling force, in this case the propelling forces are the muscles that act upon the ball to make it move, and the stronger the force applied, the more propelling force, which means the projectile (the ball) will travel farther. Seepitching,bowling.

As a weapon

Delivery projectiles

Many projectiles, e.g.shells,may carry an explosive charge or another chemical or biological substance. Aside from explosive payload, a projectile can be designed to cause special damage, e.g. fire (see alsoearly thermal weapons), or poisoning (see alsoarrow poison).

Kinetic projectiles

This section is an excerpt fromKinetic energy weapon.[edit]

TheHoming Overlay Experimentused a metal fan that was rolled up during launch and expanded during flight. The metal has five times as much destructive power as an explosive warhead of the same weight.

Akinetic energy weapon(also known as kinetic weapon, kinetic energy warhead, kinetic warhead, kinetic projectile, kinetic kill vehicle) is aprojectile weaponbased solely on a projectile'skinetic energyto inflictdamageto a target, instead of using anyexplosive,incendiary/thermal,chemicalorradiologicalpayload.All kinetic weapons work by attaining a high flight speed — generallysupersonicor even up tohypervelocity— andcollidewith their targets, converting its kinetic energy and relativeimpulseinto destructiveshock waves,heatandcavitation.In kinetic weapons withunpowered flight,themuzzle velocityorlaunch velocityoften determines theeffective rangeandpotential damageof the kinetic projectile.

Kinetic weapons are the oldest and most common ranged weapons used inhuman history,with the projectiles varying from blunt projectiles such asrocksandround shots,pointed missiles such asarrows,bolts,darts,andjavelins,to modern tapered high-velocity impactors such asbullets,flechettes,andpenetrators.Typical kinetic weapons accelerate their projectiles mechanically (bymuscle power,mechanical advantage devices,elastic energyorpneumatics) or chemically (bypropellantcombustion,as withfirearms), but newer technologies are enabling the development of potential weapons usingelectromagneticallylaunched projectiles, such asrailguns,coilgunsandmass drivers.There are also concept weapons that are accelerated bygravity,as in the case ofkinetic bombardmentweapons designed forspace warfare.

The term hit-to-kill, or kinetic kill, is also used in the militaryaerospacefield to describe kinetic energy weapons accelerated by arocket engine.It has been used primarily in theanti-ballistic missile(ABM) andanti-satellite weapon(ASAT) fields, but some modernanti-aircraft missilesare also kinetic kill vehicles. Hit-to-kill systems are part of the wider class of kinetic projectiles, a class that has widespread use in theanti-tankfield.

Wired projectiles

Some projectiles stay connected by a cable to the launch equipment after launching it:

• for guidance:wire-guided missile(range up to 4,000 metres or 13,000 feet)
• to administer an electric shock, as in the case of aTaser(range up to 10.6 metres or 35 feet); two projectiles are shot simultaneously, each with a cable.
• to make a connection with the target, either to tow it towards the launcher, as with a whalingharpoon,or to draw the launcher to the target, as agrappling hookdoes.

Typical projectile speeds

See also:Orders of magnitude (speed)andMuzzle velocity

Projectile	Speed				Specific kinetic energy(J/kg)
	(m/s)	(km/h)	(ft/s)	(mph)
Object falling 1 m (in vacuum, at Earth's surface)	4.43	15.948	14.5	9.9	9.8
Object falling 10 m (in vacuum, at Earth's surface)	14	50.4	46	31	98
Thrownclub(expert thrower)	40	144	130	90	800
Object falling 100 m (in vacuum, at Earth's surface)	45	162	150	100	980
Refined (flexible)atlatldart (expert thrower)	45	162	150	100	1,000
Ice hockey puck (slapshot,professional player)	50	180	165	110	1,300
80-lb-draw pistolcrossbowbolt	58	208.8	190	130	1,700
War arrowshot from a 150 lbsmedieval warbow	63	228.2	208	141	2,000
Blunt Impact Projectileshot from a 40mmgrenade launcher	87	313.2	285	194.6	3,785
Paintballfired from marker	91	327.6	300	204	4,100
175-lb-drawcrossbowbolt	97	349.2	320	217	4,700
6 mmAirsoft pellet	100	360	328	224	5,000
Air RifleBB 4.5 mm	150	540	492	336	11,000
Air gunpellet.177 "(magnum-power air rifle)	305	878.4	1,000	545	29,800
9×19mm(bullet of apistol)	340	1224	1,116	761	58,000
12.7×99 mm(bullet of a heavymachine gun)	800	2,880	2,625	1,790	320,000
German Tiger I88 mm(tank shell- Pzgr. 39 APCBCHE)	810	2,899	2,657	1,812	328,050
5.56×45mm(standard round used in many modern rifles)	920	3,312	3,018	2,058	470,000
20×102mm(standard US cannon round used in fighter cannons)	1,039	3,741	3,410	2,325	540,000
25×140mm (APFSDS,tankpenetrator)	1,700	6,120	5,577	3,803	1,400,000
2 kg tungsten Slug (from ExperimentalRailgun)	3,000	10,800	9,843	6,711	4,500,000
MRBMreentry vehicle	Up to 4,000	Up to 14,000	Up to 13,000	Up to 9,000	Up to 8,000,000
projectile of alight-gas gun	Up to 7,000	Up to 25,000	Up to 23,000	Up to 16,000	Up to 24,000,000
Satellite inlow Earth orbit	8,000	29,000	26,000	19,000	32,000,000
Exoatmospheric Kill Vehicle	~10,000	~36,000	~33,000	~22,000	~50,000,000
Projectile (e.g.,space debris) and target both inlow Earth orbit	0–16,000	~58,000	~53,000	~36,000	~130,000,000
7TeVparticleinLHC	299,792,455	1,079,252,839	983571079	670,616,536	~6.7 × 1020

Equations of motion

Main article:Projectile motion

An object projected at an angle to the horizontal has both the vertical and horizontal components of velocity. The vertical component of the velocity on the y-axis is given as$V_{y}=U\sin \theta$while the horizontal component of the velocity is$V_{x}=U\cos \theta$.There are various calculations for projectiles at a specific angle$\theta$:

1. Time to reach maximum height. It is symbolized as ($t$), which is the time taken for the projectile to reach the maximum height from the plane of projection. Mathematically, it is given as$t=U\sin \theta /g$where$g$= acceleration due to gravity (app 9.81 m/s²),$U$= initial velocity (m/s) and$\theta$= angle made by the projectile with the horizontal axis.

2. Time of flight ($T$): this is the total time taken for the projectile to fall back to the same plane from which it was projected. Mathematically it is given as$T=2U\sin \theta /g$.

3. Maximum Height ($H$): this is the maximum height attained by the projectile OR the maximum displacement on the vertical axis (y-axis) covered by the projectile. It is given as$H=U^{2}\sin ^{2}\theta /2g$.

4. Range ($R$): The Range of a projectile is the horizontal distance covered (on the x-axis) by the projectile. Mathematically,$R=U^{2}\sin 2\theta /g$.The Range is maximum when angle$\theta$= 45°, i.e.$\sin 2\theta =1$.

See also

• Atlatl
• Ballistics
• Gunpowder
• Bullet
• Impact depth
• Kinetic bombardment
• Shell (projectile)
• Projectile point
• Projectile use by animals
• Arrow
• Dart
• Missile
• Sling ammunition
• Spear
• Torpedo
• Range of a projectile
• Space debris
• Trajectory of a projectile

References

• Heidi Knecht (29 June 2013).Projectile Technology.Springer Science & Business Media.ISBN978-1-4899-1851-2.

External links

• Open Source Physics computer model
• Projectile Motion Applet
• Another projectile Motion Applet