The Boy Scientist: Ch. 5, Part 2

Boyle's Law 

Boyle's law is: The volume of a gas is inversely proportional to the pressure exerted on that gas. He did an experiment to prove this:

First he took a tube with one end closed, and bent that end into a J, or a shepherd's crook, and filled the tube with a little mercury so that it did not rise more in either side of the tube, but stayed on the bottom. There was air in the closed end. Then he poured in 29 inches of mercury, so that the air in the closed end occupied 1/2 the space it had occupied before. Then he poured in 29 more inches of mercury so that the air in the closed space occupied 1/3 the space it had originally occupied before the mercury was poured in. Can you tell me why the mercury did not take up the whole space? 

Here is the answer: It doesn't because the air still has the same number of particles, but it is squeezed into a smaller space. The air has a minimal amount of space it can be squeezed into. 

How a jet engine works

There is a compartment that is full of air, and there is a kind of fuel in the other. The compressor compresses the air as much as 6 times to greatly increase be greatly increased force exerted  when the air is mixed with the fuel and exploded. Some of this gas is released in thrust, flying the airplane. Before the gas escapes, it drives a turbine that works the compressor.

Bell