3 ms·
Your highlighted link is the wrong model to use here. The part you highlighted in your link is about elastic collisions in one dimension. Even with "spherical c
by hn_throwaway_99 2y ago
Your highlighted link is the wrong model to use here. The part you highlighted in your link is about elastic collisions in one dimension. Even with "spherical cow" physics, collisions like this are nearly always modeled as perfectly inelastic collisions. You don't model the cars bouncing off each other going back with the same speed that they were originally going - you model then as crashing into each other and stopping, with all of that kinetic energy converted to heat, a perfectly inelastic collision.
As per your "stationary" objections, the issue is that this is modeled as a very sturdy wall anchored to the Earth. Yes, the Earth will "recoil" some, but for all intents and purposes it can be modelled as completely stationary because its mass is so much greater than the car.
- roarcher 2y agoI don't know what you mean--there's nothing highlighted in that link when I open it. Part of it is about elastic collisions and part is about inelastic. > the issue is that this is modeled as a very sturdy wall anchored to the Earth. That's not what you modeled in the comment you linked. Your math (incorrectly) attempts to describe a car colliding with another car of equal mass. But if you're considering a "very sturdy wall anchored to the earth", then you effectively have a car colliding with the earth. Either one is fine with me, but pick one. It grinds my gears when you authoritatively call me "absolutely incorrect", "correct" me with an incorrect answer of your own, and then try to claim you were modeling something entirely different all along.
- hn_throwaway_99 2y agoDude, you seriously need to work on your reading comprehension, this conversation is like talking to a dining room table. The link I posted, https://news.ycombinator.com/item?id=40628932 https://news.ycombinator.com/item?id=40628932, clearly showed the kinetic energy math for both a car hitting a stationary wall at speed 2X, and 2 cars hitting each other each with speed X. This is basic high school math of inelastic collisions.
- roarcher 2y agoYou're right, I misread your comment, my apologies.