average of less than a watt of power from rainfall, and the maximum electricity savings would be:
Th e rainiest hour on record as of 2014 occurred in 1947 in Holt, Missouri, where about 30 centimeters of rain fell in 42 minutes. For those 42 minutes, our hypothetical house could generate up to 800 watts of electricity, which might be enough to power everything inside it. For the rest of the year, it wouldn’t come close.
If the generator rig cost $100, residents of the rainiestplace in the US — Ketchikan, Alaska — could potentially offset the cost in under a century.
Q. Using only pronounceable letter combinations, how long would names have to be to give each star in the universe a unique one-word name? —Seamus Johnson
A. Th ere are about 300,000,000,000,000,000,000,000 stars in the universe. If you make a word pronounceable by alternating vowels and consonants (thereare better ways to make pronounceable words, but this will do for an approximation), then every pair of letters you add lets you name 105 times as many stars (21 consonants times 5 vowels). Since numbers have a similar information density
—100 possibilities per character
—this suggests the name will end up being about as long as the total number of stars:
Th e stars are named Joe Biden.
I like doing math that involves measuring the lengths of numbers written out on the page (which is really just a way of loosely estimating log 10 x ). It works, but it feels so wrong.
Q. I bike to class sometimes. It’s annoying biking in the wintertime, because it’s so cold. How fast would I have to bike for my skin to warm up the way a spacecraftheats up during reentry? —David Nai
A. Reentering spacecraft heat up because they’re compressing the air in front of them (not, as is commonly believed, because of air friction).
To increase the temperature of the air layer in front of your body by 20 degrees Celsius (enough to go from freezing to room temperature), you would need to be biking at 200 meters per second.
Th e fastesthuman-powered vehicles at sea levels are recumbent bicycles enclosed in streamlined aerodynamic shells. Th ese vehicles have an upper speed limit near 40 m/s — the speed at which the human can just barely produce enough thrust to balance the drag force from the air.
Since drag increases with the square of the speed, this limit would be pretty hard to push any further. Biking at 200 m/s wouldrequire at least 25 times the power output needed to go 40 m/s.
At those speeds, you don’t really have to worry about the heating from the air — a quick back-of-the-envelope calculation suggests that if your body were doing that much work, your core temperature would reach fatal levels in a matter of seconds.
Q. How much physical space does the Internet take up? —Max L
A. Th ere are alot of ways to estimate the amount of information stored on the Internet, but we can put an interesting upper bound on the number just by looking at how much storage space we (as a species) have purchased.
Th e storage industry produces in the neighborhood of 650 million hard drives per year. If most of them are 3.5-inch drives, that’s 8 liters (2 gallons) of hard drive per second.
Th ismeans the last few years of hard-drive production — which, thanks to increasing size, represents the majority of global storage capacity — would just about fill an oil tanker. So, by that measure, the Internet is smaller than an oil tanker.
Q. What if you strapped C4 to a boomerang? Could this be an effective weapon, or would it be as stupid as it sounds? —Chad Macziewski
A. Aerodynamics aside,I’m curious what tactical advantage you’re expecting to gain by having the high explosive fly back at you if it misses the target.
1 Search for “Why don’t we try to destroy tropical cyclones by nuking them?” by Chris Landsea.
Lightning
Before we go any further, I want to emphasize something: I am not an authority on lightning safety.
I am a guy who draws
Th e rainiest hour on record as of 2014 occurred in 1947 in Holt, Missouri, where about 30 centimeters of rain fell in 42 minutes. For those 42 minutes, our hypothetical house could generate up to 800 watts of electricity, which might be enough to power everything inside it. For the rest of the year, it wouldn’t come close.
If the generator rig cost $100, residents of the rainiestplace in the US — Ketchikan, Alaska — could potentially offset the cost in under a century.
Q. Using only pronounceable letter combinations, how long would names have to be to give each star in the universe a unique one-word name? —Seamus Johnson
A. Th ere are about 300,000,000,000,000,000,000,000 stars in the universe. If you make a word pronounceable by alternating vowels and consonants (thereare better ways to make pronounceable words, but this will do for an approximation), then every pair of letters you add lets you name 105 times as many stars (21 consonants times 5 vowels). Since numbers have a similar information density
—100 possibilities per character
—this suggests the name will end up being about as long as the total number of stars:
Th e stars are named Joe Biden.
I like doing math that involves measuring the lengths of numbers written out on the page (which is really just a way of loosely estimating log 10 x ). It works, but it feels so wrong.
Q. I bike to class sometimes. It’s annoying biking in the wintertime, because it’s so cold. How fast would I have to bike for my skin to warm up the way a spacecraftheats up during reentry? —David Nai
A. Reentering spacecraft heat up because they’re compressing the air in front of them (not, as is commonly believed, because of air friction).
To increase the temperature of the air layer in front of your body by 20 degrees Celsius (enough to go from freezing to room temperature), you would need to be biking at 200 meters per second.
Th e fastesthuman-powered vehicles at sea levels are recumbent bicycles enclosed in streamlined aerodynamic shells. Th ese vehicles have an upper speed limit near 40 m/s — the speed at which the human can just barely produce enough thrust to balance the drag force from the air.
Since drag increases with the square of the speed, this limit would be pretty hard to push any further. Biking at 200 m/s wouldrequire at least 25 times the power output needed to go 40 m/s.
At those speeds, you don’t really have to worry about the heating from the air — a quick back-of-the-envelope calculation suggests that if your body were doing that much work, your core temperature would reach fatal levels in a matter of seconds.
Q. How much physical space does the Internet take up? —Max L
A. Th ere are alot of ways to estimate the amount of information stored on the Internet, but we can put an interesting upper bound on the number just by looking at how much storage space we (as a species) have purchased.
Th e storage industry produces in the neighborhood of 650 million hard drives per year. If most of them are 3.5-inch drives, that’s 8 liters (2 gallons) of hard drive per second.
Th ismeans the last few years of hard-drive production — which, thanks to increasing size, represents the majority of global storage capacity — would just about fill an oil tanker. So, by that measure, the Internet is smaller than an oil tanker.
Q. What if you strapped C4 to a boomerang? Could this be an effective weapon, or would it be as stupid as it sounds? —Chad Macziewski
A. Aerodynamics aside,I’m curious what tactical advantage you’re expecting to gain by having the high explosive fly back at you if it misses the target.
1 Search for “Why don’t we try to destroy tropical cyclones by nuking them?” by Chris Landsea.
Lightning
Before we go any further, I want to emphasize something: I am not an authority on lightning safety.
I am a guy who draws
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