ndred years later, fireworks escalated in popularity in the United States. However, the injuries resulting from their misuse, especially to children prompted government officials to greatly restrict their use, and eventually make them illegal in nearly all 50 states. The Physics Behind FireworksAll fireworks work basically on the same principals. This involves a very rapid chemical change in the interior of the firework. It is basically similar to the chemical change of a match burning, however in fireworks this process occurs much faster. The principles involved in launching fireworks are comparable to parachutes, or the technology used to launch space shuttles into outer space. The explosion in the interior of the firework creates momentum and energy, all of which is displaced in a single direction. The conservation of momentum dictates that the momentum of the whole system does not change. Therefore, if the gas from the explosion exits the back of the rocket, then the rocket must move in the opposite direction. (Or up and out and away!) Another interesting thing is that if the firework is falling and then it explodes it will continue to freefall—this causes the pattern of sparks to go out in all directions. This does not, however, alter the overall shape of the exploded firework since it will still be moving in a downward movement, giving the explosion the shape of a parasol. Should the firework explode at the peak of its height- it will explode in all directions like a dandelion. Finally, should the firework explode on its way down, an occurance that happens rarely-- it will take the shape of an inverse parasol. The main materials used in firework manufacture may be divided into several categories: Oxidizing agents, fuels, color producing agents, substances which improve effects such as color and light, and substances which produce smoke, binding agents, phlegmatizers, stabilizers, substances which accelerate or retard co...
