Kinetic energy is equal to half the mass multiplied by the velocity squared i.e. Ekin = 0.5 x m x v².
0.5 x 80 x 10² = 0.5 x 0.008 x 1000² = 4000 joules → a sprinter in action (m = 80 kg; v = 36 km/h = 10 m/s) has about the same amount of kinetic energy as a high speed bullet fired from a rifle (m = 8 grams = 0.008 kg; v = 1000 m/s).
A sprinter or a bullet having the same kinetic energy provoke completely different effects when they hit a person → the concentration of kinetic energy per unit area is extremely important in terminal ballistics.
1000 m/s = 3600 km/h = 2237 mph = 1944 knots.
A 9 mm bullet fired from a pistol reaches its target at 20 m distance after 0.06 seconds i.e. 60 milliseconds; the reaction time of a top-
A geostationary satellite orbiting the earth has a speed of approximately 11,000 km/h, so it moves much faster than projectiles → the impact of space debris or meteoroids on satellites can have devastating effects.
With its total length of about five metres, its calibre of 640 millimetres and its net mass of more than twelve tons, the “Dulle Griet” is the largest Western wrought iron bombard that remains from the Middle Ages. It fired stone projectiles of almost 300 kilogrammes. Its maximum range was about 1200 metres. The “Dulle Griet” can be viewed by the public in the Belgian city of Ghent.