6 ms·
There are three trends: bigger mass, larger sizes and taller vehicles. Which one of the above is the most consequential? I'm guessing height. at 2500 or 5000
by mc32 4y ago
There are three trends: bigger mass, larger sizes and taller vehicles.
Which one of the above is the most consequential?
I'm guessing height. at 2500 or 5000 lbs, neither is going to be pleasant when you bang in to it. size maybe there is more surface area to get hit by, but that's unlikely to be significant.
mass does influence stopping distance though, so that could be, but at the same time we now have large disc brakes with anti-skid.
- wefarrell 4y agoI got into a head on collision with an SUV that came off two wheels while rounding a curve and crossed the yellow divider right into my little car. In that case it was definitely the height that did us in.
- timellis-smith 4y agoGlad to hear that you lived to tell the tale. Sounds like a horrendous collision.
- wefarrell 4y agoMy car crumpled perfectly and my only injuries were scrapes from the airbag. The other driver broke a few ribs. I will never forget the split second I recognized there was a huge mass of metal coming straight at me at a high speed and I resigned to the fact that it would probably mean life altering injuries. Good thing I wore my seat belt!
- ajuc 4y agoE=mV^2/2 60 km/h car will kill you either way, 1 km/h car won't kill you either way, but somewhere in between there's a velocity range where a SUV will kill you and a compact car won't - simply because of the mass difference. I'd argue it's the velocity range in which a lot of collisions happen (especially in city traffic).
- 2rsf 4y agoIt is not just the mass, the design is critical as well. Check pedestrian impact tests, on regular cars pedestrians can roll over while with tall cars or SUVs they are simply splashed against it.
- mc32 4y agoI think that band where the light car is not lethal is a narrow bad. I could be wrong but I have a feeling it's sitting up high in an SUV/truck that is causing some of this.
- vihren 4y agoIts the momentum that kills you p=mV, not the kinetic energy. So I would guess that mass ia much more important.
- Ma8ee 4y agoWhy would that be? Isn't it the energy spent tearing your body apart that is relevant?
- tzs 4y agoA typical locomotive at 1 mph has more momentum than a Ford F-150 at 45 mph, but the latter is far more likely to kill you in collision so it doesn’t look like it is momentum that kills.
- pif 4y agoYou are both wrong, It's the acceleration that kills you.
- SketchySeaBeast 4y agoAcceleration, which is caused by a transfer of energy?
- ajuc 4y agoDoubling the mass of the car assuming everything else (crumple zones etc.) stays the same - doubles the acceleration experienced by the pedestrian. X_p0 = X of the pedestrian before collision X_c0 = X of the car before collision X_p1 = X of the pedestrian after the collision X_c1 = X of the car after the collision m_ = mass v_ = velocity a_ = acceleration t = time //conservation of momentum: m_p * v_p0 + m_c * v_c0 = m_p * v_p1 + m_c * v_c1 m_p * (v_p0 - v_p1) = m_c * (v_c1 - v_c0) v_p1 - v_p0 = m_c * (v_c0 - v_c1) / m_p // a = delta v / t a = (v_p1 - v_p0)/t = m_c * (v_c0 - v_c1) / (m_p * t)
- asdff 4y agoAlso, shape. Go look at the front end of a car like a ford F150. The hood is flat and sits 4 feet high. Now go look at a more compact car like a prius. The hood is low, and is angled like a wedge smooth into the windshield. When a prius hits you, its liable that you will just roll up and off of it and not get much of the force from the impact as a result. When an F150 hits you with its 4 foot tall wall of a grill straight in your chest, I don't think you will be rolling up and over. Maybe your head would just pop off from the kinetic force, sparing you from a slower death?
- musha68k 4y agoI once managed to barely jump and slide over the hood of a car that came up behind me and turned - at considerable speed - right into the pedestrian crossing I had been traversing on a green light. The driver looked right through me, didn’t even realize it until my - corner of the eye induced - leap. I would be dead for 15 years now if that would have been a SUV. Lots of people really don’t seem to have a good grasp of the sheer physics involved while driving these tanks especially.
- a4isms 4y ago> driving these tanks They are not tanks. They are suburban armoured personnel carriers.
- mc32 4y agoNot even. You see them in cities themselves. Like why? Finding large parking lots is hard and it’s by definition urban and you can’t possibly have mud or ditches to traverse in your 4x4!
- _Wintermute 4y agoEven worse is that they're becoming increasingly common in European cities that really don't have much space.
- jbay808 4y ago
- yread 4y agoHigher weight also requires thicker pillars so that the car doesn't smush you when it rolls over leading to worse visibility
- NBJack 4y agoNote that minivans have been around longer than SUVs, but do not appear to be as disproportionate in fatalities. I suspect part of this is that they are typically lower to the ground and, more importantly, tend to only weigh about 500 lbs more than the average car at ~4500 lbs. Contrast this with full size SUVs, which are often taller and weigh on average closer to ~5900 lbs.
- bluGill 4y agoThe Chevrolet suburban from 1947 was clearly a large SUV. (the suburban was introduced in 1935, but you could argue those models were station wagons, by 1947 they were clearly SUVs). The VW microbus - was from 1950. The minivan didn't become popular until 1980s, while SUVs remained the domain of niches like families too large for a minivan, or those who regularly drove off road for another decade or two. However the SUV is clearly the older of the two.
- pif 4y agoI'll always choose height for my car because I want comfort. My top priority when driving is safety for everybody, as in doing all my best to prevent accidents. My second priority is personal comfort, which helps in guaranteeing the first priority to be respected.