Did you take into account that the car is not driving directly towards the viewer?
Comment on Doppler
troyunrau@lemmy.ca 1 month ago
Okay, just back of the envelope math. Assuming the car is truly 550nm, so the blue car is 400nm, and the red car is 700nm… How fast is the car going?
Napkin math says 0.27c.
Δλ=λ(V/c)
Now someone else can figure out the kinetic energy of the car and why the whole continent just exploded…
Speiser0@feddit.org 1 month ago
troyunrau@lemmy.ca 1 month ago
I ain’t doing hyperbolic equations on my napkin ;)
burgersc12@mander.xyz 1 month ago
So about 180 million MPH. I hope he doesn’t get a ticket!
stebo02@lemmy.dbzer0.com 1 month ago
now calculate the Lorentz contraction
troyunrau@lemmy.ca 1 month ago
Instructions unclear, car stuck in dick.
lefixxx@lemmy.world 1 month ago
Why explode, the car didn’t accelerate or interact with the continent
roscoe@lemmy.dbzer0.com 1 month ago
Even ignoring the tires interacting with the road, you have air molecules.
Here is a cool What If?" from xkcd about throwing a baseball at 0.9c.
lefixxx@lemmy.world 1 month ago
Sound like a ton worth of mass would do a lot of damage indeed
NoSpotOfGround@lemmy.world 1 month ago
Wow, that seems to be the very first What If ever!
rowanthorpe@lemmy.ml 1 month ago
For the same reason this baseball causes an expanding plasma-ball disintegrating everything. Fusion with air molecules that can’t get out of the way fast enough what-if.xkcd.com/1/
Venator@lemmy.nz 1 month ago
someone else can figure out the kinetic energy of the car and why the whole continent just exploded…
It’s not on fire or melting the asphalt beneath it, so it must be really aerodynamic, and have really low rolling resistance tyres…
passiveaggressivesonar@lemmy.world 1 month ago
OK now how fast did old man’s head move
troyunrau@lemmy.ca 1 month ago
Okay, napkin math… his nose is about 20cm long, and assuming it rotated about a perfect circle. The car moved say 10m. At the speed the car is moving, it covers that distance in ~120ns. So he has to move the end of his nose around a quarter circle of radius 20cm in 120ns. Let’s say 30cm total movement, for easy math. 0.25cm/ns or 0.00025m/ns. The speed of light is 0.300m/ns, so we’re talking about ~0.001c at the tip of his nose. Which is incidentally very close to the speed of sound in air.
So, probably not quite a sonic boom off the end of his nose. Assuming my math is correct. Very strong neck muscles. Also, he’s been vapourized.
DogWater@lemmy.world 1 month ago
Ah this is so great. In the transonic regime (just below 1.0 Mach) the air moving over the surface of his nose will break the speed of sound as it gets out of the way.
TechieDamien@lemmy.ml 1 month ago
I think you missed a factor of 1000 when comparing against the speed of sound in air. I think it should be almost 1000 times the speed of sound, so definitely sonic boom and definitely vaporised!
troyunrau@lemmy.ca 1 month ago
It’s very possible. Napkins are notorious for stealing orders of magnitude.