4 ms·

Since the heavier vehicle has higher momentum, it would decelerate slower when hitting a semi-static-object, which decreases the forces on your body. The smalle

Since the heavier vehicle has higher momentum, it would decelerate slower when hitting a semi-static-object, which decreases the forces on your body. The smaller vehicle would stop much quicker and you would jerk forward. So a heavier vehicle at the same speed would probably be better, all else being equal. And that's neglecting the additional material a larger vehicle typically has that deforms over longer distance than with a shorter car.

resource_waste 2y ago
>it would decelerate slower when hitting a semi-static-object You just changed the problem.
- echoangle 2y ago
  Did I? Trees and electrical poles aren’t completely rigid, right?
  - resource_waste 2y ago
    Yeah, the point was deliberately to show that a small car performs better in such situations. If you had to change the problem, it shows you were avoiding the uncomfortable truth.
    - echoangle 2y ago
      But a small car doesn’t perform better, why would it? Surely a large car is better when driving into an electrical pole than a small car. What advantage does the small car have? Also, just to clarify, how did I change the problem? The problem with car crashes is rapid deceleration which injures you, and lighter cars are worse in that aspect compared to heavier cars.
      - resource_waste 2y ago
        Less momentum
        echoangle 2y ago
        And can you explain why less momentum is better for the passengers? The thing that injures you in an accident is acceleration (or more accurately deceleration), so you actually want more momentum. Imagine sitting in a large truck vs a kei car and driving into a brick wall. One has the chance to deform the wall which decreases the speed comparatively slowly. The other one abruptly stops when hitting the wall. Unless the collision target doesn't deform at all, the higher momentum is better. And if the target is completely solid, a larger typically has a larger crumple zone which is better, too. I cant come up with any reason to prefer the smaller car/momentum, except in very constructed scenarios (driving over a cliff with a weak fence for example).
        itishappy 2y ago
        Momentum is resistance to acceleration. Momentum protects the driver.
        K0balt 2y ago
        All things being equal, this is generally a little bit true, even for collisions with rigid, fixed obstacles - but vehicle design is critical here. For instance, a cab forward truck with no real crumple space does not benefit from mass, as the deformation of the pax compartment is the primary concern. A very lightweight vehicle that is very deformable and has a long crumple zone might outperform a heavier vehicle in terms of the acceleration imparted to the passengers. The problem is that a “fixed” solid object has effectively infinite mass. This applies when the collision displacement of the obstacle can be measured in fractions of a millimeter. In these cases, the ratio of the lightweight vehicle to the effective mass of the obstacle is effectively the same as with the heavier vehicle vs the obstacle. Here, mass pays no dividends. Only the distance / time covered during the sudden deceleration, and the integrity of the passenger compartment. Of course, the efficiency and extent of restraint systems will also play a major role. But it’s not an automatic win for heavier vehicles in this case. Notably, most collisions are not with immovable objects, but with other vehicles. In that case, mass is going to win almost every time, since the acceleration experienced by a subcompact vs a full sized SUV is about 2x, which means the forces imparted on the passengers in terms of static loads on their bodies and bones will be 4x. For passenger survivability in most accidents, the incentives fall heavily towards using the heaviest well constructed vehicle that you can afford.
  - mrguyorama 2y ago
    To a car? Many trees are! They are quite rigidly affixed to the ground.
    - echoangle 2y ago
      So many are and some aren't. So in many cases it doesn't matter which car you're in, and in some cases the heavy car is better. That means the heavy car is still net better. I still haven't seen a single argument why a smaller car would be better in a collision.
- itishappy 2y ago
  Not really, the car itself is a semi-static object, even if you're driving a block of raw steel.
  - resource_waste 2y ago
    I did automotive safety and I can assure you, these act as static for all intensive purposes. Being a skeptical Socrates doesnt change that the momentum is significantly higher, and you arent moving that pole any significant distance. I'm not sure why there is such a strong denial of reality here. Is it ego?
    - floxy 2y ago
      https://www.dictionary.com/e/for-all-intents-and-purposes-vs-for-all-intensive-purposes/ https://www.dictionary.com/e/for-all-intents-and-purposes-vs...
    - itishappy 2y ago
      Crumple zones have been a thing for almost a century. Momentum doesn't matter. It matters in a vehicle on vehicle collision, but since the pole is essentially infinite I'm not sure why you're bringing it up. Acceleration is what impacts the human body, and it's determined by speed and distance. For the same speed, a larger car will have a longer distance to stop, therefore lower acceleration, and less force on the body.
    - echoangle 2y ago
      Even if you assume that the pole doesn't move at all, having less momentum doesn't help you. A smaller car isn't better, in the best case it is equal. But a larger car probably also has a larger crumple zone so it is still better. You still haven't given a single reason why a smaller car would have an advantage.

resource_waste 2y ago

>it would decelerate slower when hitting a semi-static-object You just changed the problem.

echoangle 2y ago
Did I? Trees and electrical poles aren’t completely rigid, right?
- resource_waste 2y ago
  Yeah, the point was deliberately to show that a small car performs better in such situations. If you had to change the problem, it shows you were avoiding the uncomfortable truth.
  - echoangle 2y ago
    But a small car doesn’t perform better, why would it? Surely a large car is better when driving into an electrical pole than a small car. What advantage does the small car have? Also, just to clarify, how did I change the problem? The problem with car crashes is rapid deceleration which injures you, and lighter cars are worse in that aspect compared to heavier cars.
    - resource_waste 2y ago
      Less momentum
      - echoangle 2y ago
        And can you explain why less momentum is better for the passengers? The thing that injures you in an accident is acceleration (or more accurately deceleration), so you actually want more momentum. Imagine sitting in a large truck vs a kei car and driving into a brick wall. One has the chance to deform the wall which decreases the speed comparatively slowly. The other one abruptly stops when hitting the wall. Unless the collision target doesn't deform at all, the higher momentum is better. And if the target is completely solid, a larger typically has a larger crumple zone which is better, too. I cant come up with any reason to prefer the smaller car/momentum, except in very constructed scenarios (driving over a cliff with a weak fence for example).
      - itishappy 2y ago
        Momentum is resistance to acceleration. Momentum protects the driver.
        K0balt 2y ago
        All things being equal, this is generally a little bit true, even for collisions with rigid, fixed obstacles - but vehicle design is critical here. For instance, a cab forward truck with no real crumple space does not benefit from mass, as the deformation of the pax compartment is the primary concern. A very lightweight vehicle that is very deformable and has a long crumple zone might outperform a heavier vehicle in terms of the acceleration imparted to the passengers. The problem is that a “fixed” solid object has effectively infinite mass. This applies when the collision displacement of the obstacle can be measured in fractions of a millimeter. In these cases, the ratio of the lightweight vehicle to the effective mass of the obstacle is effectively the same as with the heavier vehicle vs the obstacle. Here, mass pays no dividends. Only the distance / time covered during the sudden deceleration, and the integrity of the passenger compartment. Of course, the efficiency and extent of restraint systems will also play a major role. But it’s not an automatic win for heavier vehicles in this case. Notably, most collisions are not with immovable objects, but with other vehicles. In that case, mass is going to win almost every time, since the acceleration experienced by a subcompact vs a full sized SUV is about 2x, which means the forces imparted on the passengers in terms of static loads on their bodies and bones will be 4x. For passenger survivability in most accidents, the incentives fall heavily towards using the heaviest well constructed vehicle that you can afford.
- mrguyorama 2y ago
  To a car? Many trees are! They are quite rigidly affixed to the ground.
  - echoangle 2y ago
    So many are and some aren't. So in many cases it doesn't matter which car you're in, and in some cases the heavy car is better. That means the heavy car is still net better. I still haven't seen a single argument why a smaller car would be better in a collision.
itishappy 2y ago
Not really, the car itself is a semi-static object, even if you're driving a block of raw steel.
- resource_waste 2y ago
  I did automotive safety and I can assure you, these act as static for all intensive purposes. Being a skeptical Socrates doesnt change that the momentum is significantly higher, and you arent moving that pole any significant distance. I'm not sure why there is such a strong denial of reality here. Is it ego?
  - floxy 2y ago
    https://www.dictionary.com/e/for-all-intents-and-purposes-vs-for-all-intensive-purposes/ https://www.dictionary.com/e/for-all-intents-and-purposes-vs...
  - itishappy 2y ago
    Crumple zones have been a thing for almost a century. Momentum doesn't matter. It matters in a vehicle on vehicle collision, but since the pole is essentially infinite I'm not sure why you're bringing it up. Acceleration is what impacts the human body, and it's determined by speed and distance. For the same speed, a larger car will have a longer distance to stop, therefore lower acceleration, and less force on the body.
  - echoangle 2y ago
    Even if you assume that the pole doesn't move at all, having less momentum doesn't help you. A smaller car isn't better, in the best case it is equal. But a larger car probably also has a larger crumple zone so it is still better. You still haven't given a single reason why a smaller car would have an advantage.