4 ms·

This momentum argument doesn't follow. First you calculate the momentum of the vehicle, then you compare it to an impact without describing exactly what you're

This momentum argument doesn't follow. First you calculate the momentum of the vehicle, then you compare it to an impact without describing exactly what you're comparing. However, the momentum of the vehicle will absolutely not be completely transferred to the person in an collision, and so will be not much like hitting the ground at terminal velocity. And why are we talking about momentum anyways? A fully loaded tractor trailer weighs about 80,000 lbs (~ 36,000 kg). Therefore, a tractor trailer traveling at 5 mph (~2 m/s) has a total momentum of 72,000 kg*m/s. By your argument, all tractor trailers driving through a city are grossly negligent.

engineeringwoke 4y ago
It's just another engineer being an armchair physicist. Nothing to be alarmed about
- sandworm101 4y ago
  An engineer being an armchair physicist being an armchair lawyer.
- bozhark 4y ago
  The _numbers_ Mason, they mean something!
kube-system 4y ago
And getting shot with a handgun is around 2 or 3 kg*m/s. Much less negligent, clearly!
- trgn 4y ago
  You die from the perforation wound and organ damage, not the impact.
  - kube-system 4y ago
    I understand, that’s (part of) my point. The transfer of momentum is more important than how much exists. But more broadly, negligence isn’t measured in kg*m/s.
    - trgn 4y ago
      We totally should.
trgn 4y ago
I think we're overextending the point a little, and apologies if my point did not get across well. What I wanted to illustrate was that those kind of speeds, in heavy vehicles, in cities, on surface streets, are negligent - spiritually. The sheer amount of damage that can be inflicted, in the blink of an eye, by a moment of inattention, is beyond measure (literally, that 67k number looks goofy, unreal, but it's cold hard physics). Our traffic laws are wrong, our streets are wrong. We don't tolerate that anywhere else. On a factory floor with dangerous machinery there are higher standards of safety than our public realm. This news article is the perfect illustration. Good chance the driver fell asleep, or was distracted in some way (totally normal human traits, btw, and does not make somebody a bad person). Yet the lawyer claims, that at 75mph in a 5000 pound car, this is basically just worth a speeding ticket. That's an enormous disconnect. That delta between responsibility and accountability is totally totally out of wack for drivers. An enormous amount of responsivblity (67k kg*m/s worth of it), and very little accountability ($100 speeding ticket). And yes, at slow speeds, there's just a lot more slack in the system. The driver of a 5mph tractor trailer has a lot of time to react, so does every one around them, stopping distances are exponentially lower etc... It doesn't change the fact that it will level a house, and so we should have extremely high standards.
- judge2020 4y ago
  > but it's cold hard physics It is if you assume the car is a vintage box car from before the 80's where you might or might not have airbags at all. New cars are designed to crumble and deploy airbags to absorb that impact so that the squishy humans inside the car don't experience anything nearly that high. Nowadays the biggest risk is speeding, as it negates the advances in car safety. > a 5 mph increase in the maximum state speed limit was associated with an 8 percent increase in fatality rates on interstates and freeways and a 3 percent increase on other roads https://www.iihs.org/topics/speed#effects-of-speed-limits-on-safety:~:text=An%20IIHS%20study%20examined%20longer%2Dterm%20changes.%20During%201993%2D2017%2C%20a%205%20mph%20increase%20in%20the%20maximum%20state%20speed%20limit%20was%20associated%20with%20an%208%20percent%20increase%20in%20fatality%20rates%20on%20interstates%20and%20freeways%20and%20a%203%20percent%20increase%20on%20other%20roads%20(Farmer%2C%202019) https://www.iihs.org/topics/speed#effects-of-speed-limits-on....

engineeringwoke 4y ago

It's just another engineer being an armchair physicist. Nothing to be alarmed about

sandworm101 4y ago
An engineer being an armchair physicist being an armchair lawyer.
bozhark 4y ago
The _numbers_ Mason, they mean something!

kube-system 4y ago

And getting shot with a handgun is around 2 or 3 kg*m/s. Much less negligent, clearly!

trgn 4y ago
You die from the perforation wound and organ damage, not the impact.
- kube-system 4y ago
  I understand, that’s (part of) my point. The transfer of momentum is more important than how much exists. But more broadly, negligence isn’t measured in kg*m/s.
  - trgn 4y ago
    We totally should.

trgn 4y ago

I think we're overextending the point a little, and apologies if my point did not get across well. What I wanted to illustrate was that those kind of speeds, in heavy vehicles, in cities, on surface streets, are negligent - spiritually. The sheer amount of damage that can be inflicted, in the blink of an eye, by a moment of inattention, is beyond measure (literally, that 67k number looks goofy, unreal, but it's cold hard physics). Our traffic laws are wrong, our streets are wrong. We don't tolerate that anywhere else. On a factory floor with dangerous machinery there are higher standards of safety than our public realm. This news article is the perfect illustration. Good chance the driver fell asleep, or was distracted in some way (totally normal human traits, btw, and does not make somebody a bad person). Yet the lawyer claims, that at 75mph in a 5000 pound car, this is basically just worth a speeding ticket. That's an enormous disconnect. That delta between responsibility and accountability is totally totally out of wack for drivers. An enormous amount of responsivblity (67k kg*m/s worth of it), and very little accountability ($100 speeding ticket). And yes, at slow speeds, there's just a lot more slack in the system. The driver of a 5mph tractor trailer has a lot of time to react, so does every one around them, stopping distances are exponentially lower etc... It doesn't change the fact that it will level a house, and so we should have extremely high standards.

judge2020 4y ago
> but it's cold hard physics It is if you assume the car is a vintage box car from before the 80's where you might or might not have airbags at all. New cars are designed to crumble and deploy airbags to absorb that impact so that the squishy humans inside the car don't experience anything nearly that high. Nowadays the biggest risk is speeding, as it negates the advances in car safety. > a 5 mph increase in the maximum state speed limit was associated with an 8 percent increase in fatality rates on interstates and freeways and a 3 percent increase on other roads https://www.iihs.org/topics/speed#effects-of-speed-limits-on-safety:~:text=An%20IIHS%20study%20examined%20longer%2Dterm%20changes.%20During%201993%2D2017%2C%20a%205%20mph%20increase%20in%20the%20maximum%20state%20speed%20limit%20was%20associated%20with%20an%208%20percent%20increase%20in%20fatality%20rates%20on%20interstates%20and%20freeways%20and%20a%203%20percent%20increase%20on%20other%20roads%20(Farmer%2C%202019) https://www.iihs.org/topics/speed#effects-of-speed-limits-on....