Why do you hear a thunderclap when the sound barrier is broken?
If you throw a ball at 10 Km/hr when stationary, the ball will begin travelling at 10 Km/hr, as it travels through air friction will slow it and it will come to a halt eventually. Let us say you were travelling in a car at 60 Km/hr and threw the same ball, depending on which direction you threw the ball in, it will either travel at 70 Km/hr or 50 Km/hr (for the sake of simplicity, I am not considering vectors).
Unlike the ball, sounds tends to travel at a constant speed depending on the medium that it is travelling in. Also, it is a pressure wave unlike light, which is a transverse wave. The wave leaves the the source and moves at a constant speed through the medium, which may be air, water or even a solid.
This is what a light wave looks like.
This is what a sound wave looks like.
Generally sound travels faster in solids compared to liquids, faster in liquids than in gases. Sound travels at about 1235 Km/hr in air at sea level. It travels a little slower as you go higher since air becomes rarer.
Unlike the case of the ball mentioned above, sound being produced by a jet engine will travel at a constant speed. When the jet begins to approach the speed of sound, every successive pressure wave begins to arrive faster and faster. When a jet reached the speed of sound, the next sound wave arrives before the previous one has been able to move.
Its like someone coming running from behind and slapping you.
This results is what is called interference. In this case constructive interference. The two sound wave collide with one another resulting in the Sonic Boom.
Anton Franz Mesmer was a German physician in the 18th Century experimenting with magnets to cure maladies. He began by using magnets and soon discovered that he did not even need them. He referred to his approach to curing as Animal Magnetism. Nobody at the time understood what was happening. In the 19th Century one James Braid studied what Mesmer did and proposed to call it hypnosis.
Mesmerised is a word derived from his name to describe a person who is completely captivated.
I keep learning random stuff, here and there. I never document these things although they might contribute to an interesting read.
I also have a writing problem. It takes me a lot of time to think through things and condense it into a blog AND I am mightily indisciplined.
So for the benefit of other and in order to be able to push out some content regularly, I am going to start writing ‘Did you know?’ It would generally contain something I learnt that I did not already know.
At time, you might already know it, which is fine; other times you might be surprised. If you like this leave a comment, so I know what all the 12 people reading this think about it.
So here goes…
Our blood carries oxygen from our lungs to all of the vital organs in our body. This oxygen is used to burn glucose in the blood stream to produce energy to keep all the organs functioning.
The body does not have any way of detecting the oxygenation levels of blood, but it can detect the CO2 level in the blood.
If you breathe in and hold your breath, you feel this intense need to release your breath because the body wants to push out CO2, not because it seeks Oxygen.
Freedivers use this fact to dive even upto 100 meters without any oxygen. They just keep breathing out enough CO2 and the body is happy!