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A scientific fact/tidbit you recently learned that you thought was interesting

A car's stopping distance from 30mph is ~double the stopping distance from 20mph (Here in Wales the 'built up area' speed limit is about to be dropped from 30mph to 20mph, and a pamphlet delivered locally included that factoid).
 
GlennB said:
A car's stopping distance from 30mph is ~double the stopping distance from 20mph (Here in Wales the 'built up area' speed limit is about to be dropped from 30mph to 20mph, and a pamphlet delivered locally included that factoid).
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Yup, kinetic energy =MV^2/2.
With V = 20, V^2 = 40
With V = 30, V^2 = 90
It's not just ~double, it's 90/40 = 2.25 times the energy that has to be stopped.
 
Puppycow said:
Yeah, have you never noticed a similar phenomenon? You would only notice if you use some sort of wireless technology like BlueTooth or Wi-Fi near a microwave oven while it is running.
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I have my desktop connected to the internet through the power lines. The microwave oven reduces the speed and reliability considerably, but no other electrical appliance does. My theory is that the power lines are also affected by leaking microwave radiation.
 
I have not noticed any issue with my microwave and Wi Fi, though it is not in the path of the signal either. I tested with a phone right in front of it, and it was not disturbed. I don't know what's available these days, but Radio Shack used to sell a little microwave detector that, while hardly a scientific instrument, could detect leakage of doors and the like.

ETA, oh, I was writing a long discourse on split-phase electrical systems and how things can interfere with each other, but I just noticed you're in Denmark! Alas, I do not know how the current works there. In the US, split phase power can cause problems if two things are on the same side of the double-voltage input line, but can be improved if you switch one thing to the other side. But I don't know if that's the case in Denmark. It might, though, be worth checking if you can plug the internet signal into a different outlet, and see if there's any change.
 
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I used to get some interference on the speakers on my TV (probably an early flat screen) which I have on the kitchen table. I finally figured out it was something from the phone that was doing it - either wi-fi or Bluetooth. But I haven't seen that problem for several years.

I often forget that there was some warning of having a pacemaker and using a microwave. I haven't noticed any ill effects in my normal use. I do remember being cautioned about using a chainsaw (or anything that produces a magnetic field.)
 
Leaky microwave ovens would interfere with 2.4GHz wifi but shouldn't affect 5GHz wifi. Most hubs and devices these days can use both and don't bother the user with such details as telling you which one is in use.

I've just once noticed a file download stutter when the microwave was started. That was on an old laptop which only used 2.4GHz wifi and I was sitting directly upstairs from the microwave, like 8 or 9 feet away.
 
bruto said:
ETA, oh, I was writing a long discourse on split-phase electrical systems and how things can interfere with each other, but I just noticed you're in Denmark! Alas, I do not know how the current works there. In the US, split phase power can cause problems if two things are on the same side of the double-voltage input line, but can be improved if you switch one thing to the other side. But I don't know if that's the case in Denmark. It might, though, be worth checking if you can plug the internet signal into a different outlet, and see if there's any change.
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I am not well-versed in these matters, but multi-story house has three phases, of which one is used in each flat for 230 volt when combined with neutral, and for those appliances that need 400 volt, two phases are combined with each other. Is this what you are referring to as “split phase”?
 
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