How To - by Randall Munroe

Published:

How To - by Randall Munroe

Read: 2024-09-15

Recommend: 6/10

This book cleverly combines physics concepts with a comic book format, making complex scientific ideas more accessible and engaging. My favorite chapter is How to play the piano.

Notes

Here are some text that I highlighted in the book:

  1. Playing the piano isn’t very hard, in the sense that the keys are all easy to reach and they don’t take very much force to push down. Playing a piece of music is just a matter of finding out which keys you need to press, then pressing them at the right time.

  2. the sound made by the leftmost key on a full-size piano is 27 hertz (Hz)—which means the string oscillates 27 times per second—while the rightmost key’s main frequency is 4,186 Hz. The ones in between form a regular scale, spanning a range of about 7 octaves. Each key has a frequency roughly 1.059 times higher than the one to its left—that’s $2^{1/12}$, which means that every 12 keys, the frequency doubles.

  3. On the left end of the piano, covering the human hearing range is a little easier. The lower limit of human hearing is somewhere around 20 Hz, 7 Hz lower than the lowest key on the piano.

  4. High-frequency sounds are absorbed by air as they travel through it, so they fade out quickly. That’s why nearby thunder makes a higher-pitched “cracking” sound, while faraway thunder makes a low rumble. They both sound the same at the source, but over a long distance, the high-frequency components of the thunder are muffled and only the low-frequency ones reach your ear.

  5. Sounds below the normal hearing limit of 20 Hz are called infrasound

  6. while ultrasound travels less far than normal sound, infrasound travels farther. An infrasonic signal with a frequency below 1 cycle per second—1 Hz—can travel all the way around the planet.

  7. One of the most common infrasound tones is produced by waves on the open ocean. As the sea rises and falls, it presses rhythmically against the air, behaving like the surface of a huge, slow music speaker—the loudest, deepest subwoofer on the planet.

  8. Piano strings won’t work for producing ultrasound because the vibrations are too small and fade too quickly—even within the normal range of pitches, pianos typically need multiple strings for the highest notes in order to make them loud enough.

  9. Modern internal combustion engines can convert about 30 percent of the input fuel energy into useful work.

  10. Comedian Mitch Hedberg once commented that an escalator can never break; it can only become stairs.

  11. we’re solving this problem the way we so often do: by trying not to think about it and hoping it goes away.