Alex Stocks, age 8, of Victoria, B.C... for his question:
What happens when a Jet breaks the sound barrier?
The noise is like a clap of thunder and sometimes strong enough to shatter windows. But actually, this big racket cannot hurt us. In fact, those high flying fast jets are up there to protect us, just in case. The big bang is caused by nothing more than air, as the fast jet bashes through it. In a way, the sound barrier bang is related to a clap of thunder. Both are caused by air going somewhere in a hurry.
Air is made of tiny particles of gases, too small, of course for our eyes to see. In a thimbleful of ordinary air, there are at least three million, million of these tiny particles. All of them are rushing around in a great hurry, crashing into each other many times each second.
These air particles carry sound towards our eyes. When you beat a drum, the top of the drum jogs or vibrates to and fro. This vibrating jogs the air particles next to the drum head, and they vibrate. They Jog the particles behind them and so on until a line of vibrating particles reaches your ears.
This vibrating of air particles is the sound which reaches our ears. It seems to happen very fast indeed, For instance, when you drop a cup in the kitchen, the sound reaches Mother's ears in no time at all. Actually, it took a small part of a second for the air particles to carry the sound of the breaking cup to Mother's ears.
We call this the speed of sound. For sound can travel so fast and no faster. This is because the little air particles can move so fast and no faster. It takes sound about five seconds to travel one mile. Not so long ago, planes that tried to fly faster than the speed of sound got into trouble.
When they flew at one mile in five seconds, they seemed to meet a solid wall. This wall was called the sound barrier.
Then someone figured out that the trouble might be because air particles cannot move faster than the speed of sound. They could not get out of the way in time to let the plane fly through them. Instead, countless trillions of particles piled up ahead of the speeding plane. This created what seemed like a solid wall.
New planes were designed to cope with the problem. They were streamlined and given short wingm that sloped backward. These designs helped the planes crash through the sound barrier by brute force. When this happens, it is almost like breaking through a solid wall of air. The air piled up ahead of a plane is shattered and explodes with a great bang. This is the bang that you hear when one of those fast little jets breaks the sound barrier.