The Physics of Fireworks
"What are fireworks like?" she had asked.
"They are like the Aurora Borealis" said the King, "only much more natural. I prefer them to stars myself, as you always know when they are going to appear…"
-Oscar Wilde The Remarkable Rocket
Why did we choose the topic of fireworks?
Fireworks have been a traditional means of celebration in Hawaii for generations. They are fun to watch and even more fun to set off. Most of all, we chose this topic because we like to blow stuff up and cause our own non violent explosions.
In order to better understand the physics of fireworks, we decided to investigate the history behind the understanding and conception of fireworks. Originally, fireworks were created in China. The art of combining pyrotechnics and casing them has existed since the sixth century. The Chinese made explosives as defense mechanisms against the Mongol invaders in the late 13th century, thereby employing pyrotechnics for other means than art. From China, fireworks proliferated to Europe where the first records indicate gunpowder rockets as early as 1258 AD.
Despite China's initial invention and progress, Europe exceeded the technology in the 14th century, around the same time the gun was invented. Gunpowder and shot for the military were made by firemakers, or skilled military tradesmen. They were also required to make victory fireworks for celebrations of victory and times of peace.
Throughout the Renaissance, rival philosophies of pyrotechnics evolved. One originated in Italy, and the other in Germany. The Italians believed that pyrotechnics should entail the use of elaborate fireworks, while the German school emphasized scientific advancements and the use of technology. Both Italian and German schools added greatly to the furthering of pyrotechnics.
By the 1600's, fireworks were mainstream entertainment and were used on an extraordinary scale in Europe. Two hundred 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 Fireworks
All 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...