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What's red and bad for your teeth? (sh.itjust.works)
submitted 4 days ago by to c/dadjokes@lemmy.world
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A brick.

If this one already made an appearance on here, I'm sorry. Just got reminded of it while thinking about idioms for hefty books, in english I couldn't find any. In my first language we would say "it's a brick"

Alt version of this joke:

What's red and good for a cop's teeth?Correct! A brick!

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[–] 2 points 2 days ago (3 children)

I'm certain there's someone out there who can tell us what speed, probably a percentage of the speed of light, an average brick needs to move at in order to blueshift to looking blue. And I'm also certain there's someone out there who can tell us what collateral effects that'll have on the rest of the world.

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  • [–] 3 points 2 days ago (1 child)

    The formula is wavelength shift over the normal wavelength, multiplied by c. Red is let's say around 600nm and blue is 450. That makes it 150/600. So about a quarter of the speed of light. My initial thought is 2kg mass traveling at a quarter speed of light would probably have a fuck ton of energy that its collision with the atmosphere would not result in friction but a big kaboom.

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  • [–] 2 points 2 days ago

    The formula for kinetic energy is

    KE = 1/2 * m * v^2^

    where m is mass in kilograms and v is velocity in meters per second. Since we already have all of the values, it should just be a quick calculation.

    KE = 1/2 * m * v^2^ = 1/2 * 2 * (299,792,458/4)^2^ = 5.6*10^15^ Joules

    According to Wolfram Alpha, 5.6PJ is about 60% the impact energy that formed Meteor Crater in Arizona .

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