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For projectiles in unpowered flight, its velocity is highest at leaving the muzzle and drops off steadily because of air resistance.Projectiles traveling less than the speed of sound (about 340 m/s (1,100 ft/s) in dry air at sea level) are subsonic, while those traveling faster are supersonic and thus can travel a substantial distance and even hit a target before a nearby observer hears the ...
Bullets used in many cartridges are fired at muzzle velocities faster than the speed of sound [10] [11] —about 343 metres per second (1,130 ft/s) in dry air at 20 °C (68 °F)—and thus can travel substantial distances to their targets before any nearby observers hear the sound of the shots.
Detonation velocity is the speed with which the detonation shock wave travels through the explosive. It is a key, directly measurable indicator of explosive performance, but depends on density which must always be specified, and may be too low if the test charge diameter is not large enough.
Projectiles are described by a ballistic coefficient, or BC, which combines the air resistance of the bullet shape (the drag coefficient) and its sectional density (a function of mass and bullet diameter). The deceleration due to drag that a projectile with mass m, velocity v, and diameter d will experience is proportional to 1/BC, 1/m, v² and ...
The velocity of the bullet is a more important determinant of muzzle energy. For a constant velocity, if the mass is doubled, the energy is doubled; however, for a constant mass, if the velocity is doubled, the muzzle energy increases four times. In the SI system the above E k will be in unit joules if the mass, m, is in kilograms, and the ...
For example: the energy of TNT is 4.6 MJ/kg, and the energy of a kinetic kill vehicle with a closing speed of 10 km/s (22,000 mph) is 50 MJ/kg. For comparison, 50 MJ is equivalent to the kinetic energy of a school bus weighing 5 metric tons, traveling at 509 km/h (316 mph; 141
The speed of sound is the distance travelled per unit of time by a sound wave as it propagates through an elastic medium. More simply, the speed of sound is how fast vibrations travel. At 20 °C (68 °F), the speed of sound in air, is about 343 m/s (1,125 ft/s; 1,235 km/h; 767 mph; 667 kn), or 1 km in 2.91 s or one mile in 4.69 s.
In this instance, heavier bullets are loaded in standard ammunition, which reduces muzzle velocity below the speed of sound. As an example, the very common 9×19mm Parabellum standard military round is a 7.5 g (116 gr) bullet at velocities typically around 360 m/s (1,200 ft/s). Subsonic loads for 9×19mm Parabellum commonly use 9.5 g (147 gr ...