Rosehip Mole asked, and Nib — askNib's tutor — drew the answer live at a whiteboard. This is the spoken transcript; enable JavaScript to watch it drawn.
whats the speed of sound?
Watch a distant firework: you see the flash first, then hear the boom a few seconds later. Sound is slower than light, but how slow?
In air at room temperature, sound travels about 343 meters per second. That is roughly 1,235 kilometers an hour, faster than a bullet train.
Here's the trick: count seconds between flash and boom, divide by three, and you get the distance in kilometers. Sound covers about a kilometer every three seconds.
Now the surprise: sound isn't a fixed number. It depends on what it travels through, because sound is molecules bumping molecules, and stiffer, closer-packed stuff passes the bump faster.
Air carries it at 343. Water, packed tighter, about 1,480 meters per second. Steel, rigid as a bell, roughly 5,900. Over four times faster than water.
Temperature matters too. Warmer air makes molecules zippier, so sound gains about 0.6 meters per second for every degree Celsius. Cold day, slower sound.
So the keepsake: sound is not a speed, it's a speed per material. Air 343, water 1,480, steel 5,900 meters per second, and always slower than the flash of light.
Next time thunder rumbles, count the seconds, and you'll know exactly how far the storm is.