Smyths

I know it from the tribute plaque to the Apollo 1 astronauts who sadly passed in a tragic fire during ground tests.

At the risk of feeding the troll, here is the math you are suggesting we do, which disproves all of your arguments. It pains me how confidently you speak of a topic you are clearly so uneducated about: your physics mentors should be disappointed in you.

Conservation of linear momentum:

m₁v_1i + m₂v_2i = m₁v_1f + m₂v_2f

Let the vehicle be m₁ and the human m₂. Let the human’s initial velocity be zero. Let us further assume an inelastic collision: the human and vehicle end up at the same final speed v_1f=v_2f=v_f.

Thus:

m₁v_1i = (m₁+m₂)v_f

What we are concerned of is the ratio of initial vehicle speed, v_1i, to post-collision speed v_f. Your argument is that a lighter vehicle will have a larger drop-off in speed, recovering energy and reducing the severity of the collision. If you were right, the ratio v_1i/v_f should be less than 1.0, and be significantly different for a heavy and light vehicle. We will prove this wrong shortly.

Rearranging:

v_1i/v_f = m₁/(m₁+m₂)

Already it is abundantly clear that when m₁ >> m₂, v_1i/v_f will be 100%. I will leave you no room for counterargument here by working two examples. Take the most popular pickup truck, the Ford F150, at 2125 kg. Take one of the smallest compact cars, a Honda Fit, at 1130 kg. Take the average adult human, at 65 kg.

For the F150: v_1i/v_f = 2125/(2125+65) = 97%

For the Honda fit: v_1i/v_f = 1130/(1130+65) = 95%

At 35 mph, that’s a difference in speed delta of 0.7 mph, which is absolutely insufficient to explain the delta in injury severity presented in this article.

This proves what everyone knew all along: vehicle mass is insignificant in crash severity with a pedestrian because the masses of the two objects are so different. When the masses are similar (e.g. a small car colliding with a big car) yes, mass is important. But that’s not what is being discussed and is not your argument.

I hope you go back to school and learn the basics before confidently acting superior. Take your downvotes and learn from this to do better.

Survivorship bias?

Two facts:

1. The average occupancy of a car in my North American city is 1.2 people per car. This does not vary much by city.
2. Autonomous vehicles will almost certainly be worse for traffic than human driven cars. They will circle empty with no passengers and drive to pick up passengers empty (dead heading) even with a fully rideshare system. If there is widespread private ownership of autonomous vehicles (and you bet your butt that car companies will campaign for this aggressively to keep sales up), the dead heading problems only multiply. If you don’t believe me, look up any recent literature on the topic: by most accounts it will be worse, not better. Dead heading is only the tip of the iceberg of problems there.

I as pro-EV as the best of them. A cradle to grave emissions drop of 40% is a great step forward on reducing transport emissions (public transport and active transportation are a whole other aspect of this we’ll avoid here). However, characterizing the energy gap for EV charging as a non-issue is disingenuous.

You’ve correctly pointed out that peak hours are when the grid is most strained and vulnerable. Well, if most everyone who drives to work starts charging their EV when they get home from work, that is at the highest peak of the day: around 5-7pm. It’s the addition to the peak curve that’s the real concern. In most places, that means triggering on fossil fuel burning facilities to meet that peak demand. It also means increased peak loads on the transmission infrastructure that could overwhelm it.

That being said, there are some simple solutions: e.g. charge EVs on off-peak hours, smoothing out the demand on the grid. Where I live there is already an incentive to charge overnight in the form of ultra low overnight rates. I’m sure we’ll find the solutions, but please don’t pretend it’s not a problem.

Reminder to remove the ?si= and everything after in your youtube links. It’s a tracker uniquely tied to you and your watch history and the links work fine without it.

A free market requires stringent regulation to function humanely and morally. The two are at odds with each other. My final sentence is a critique of neoliberalism, an ideology in which regulation is reduced and power is given to corporate entities and away from regulators. It’s been impossible to escape in politics since Thatcher and Reagan, and leads to some of the worst aspects of today’s society that we havr to suffer. One of which is the poor people who bought a car assuming it’d be safe, just to find that the companies saved a quick buck to their loss. I hope the people win these lawsuits, but I doubt the justice system has the teeth (or willingness) to prosecute this negligence as it should be.

No, but it is the result of deregulation. Similar models sold in Canada don’t have this issue because (drumroll please), federal regulations require immobilizers on new cars. Free market at work folks.