All you guitar players out their ever wonder why your instrument sounds SO different and unique compared to say a tuba? Well the simple answer is physics. I hope that by the end of this post, you will understand why.
A guitar string is a common example of a string fixed at both ends which is elastic (meaning springy and flexible) and can vibrate. The vibrations of strings on the guitar are called standing waves, and they represent the relationship between wavelength and frequency. This simple equation can be found on the regents reference table under the categorie "waves."
The speed (v) of waves on a string depends on the string tension and waves travel faster on a tighter string; therefore, frequency would be greater on a tighter string and lower on a thicker string.
To have different pitches (frequencies) from the strings, the guitar must have different wave speeds, or else no one would want to listen to you, hate to break it to ya bud but one note for an entire song wouldn't get you too many fans! If you could only vary pitch by only varying tension, the high strings would be very tight and the low strings would be very loose and it would be very difficult to play (so you can thank physics for saving your pick and your fingers)! It is much easier to play a guitar if the strings all have roughly the same tension; for this reason, the lower strings have higher mass density, by making them thicker and, for the 3 low strings, wrapping them with wire. That is why strings on a guitar vary in thickness and texture, some are thin and others are thick and tough in texture; because of this your instrument is able to strum at all different frequencies and make these beautiful sounds.
For a quick brief summary, a guitar string sound consists of standing waves; the fundamental wavelengh is twice the length of the vibrating part of the string. And lastly, the Western musical scale is based on the overtone series for a string. So the next time you're strumming along and being a rockstar don't forget that physics is the reason why your guitar sounds so good.
For some more information and knowledge to expand your thought check out this cool youtube video on the relationship between physics and the guitar!