3 ms·

1200kg for the car divided by 4 points of surface contact („wheels“) equals 300kg. Wikipedia says an Elephant is 5.2-6.9t. So.. well.. seems a bit off.

rikkipitt 5y ago
Yep, also known as "corner weight" w.r.t. cars. Strange how they missed it. I wonder if it's a common misconception?
jve 5y ago
Plus if it was back of the car, it is more ligtweight. Moreover, that tire surface is much bigger and by part rests outside of material bounds.
dylan604 5y ago
Isn't an elephant's weight also distributed on 4 points of surface contact ("feet")?
- aaron695 5y ago
  That's what I thought, then I realised they took into account walking. The forelimbs also take more weight (60%) Foot pressure distributions during walking in African elephants https://royalsocietypublishing.org/doi/10.1098/rsos.160203 https://royalsocietypublishing.org/doi/10.1098/rsos.160203 Unlike a horse they never have all feet off the ground.
JKCalhoun 5y ago
Typical car tires are inflated to 35 PSI or so. There is a surprisingly large "footprint" from a tire supporting a car. I think the PSI in their test is fairly small. While I'm sure finding an elephant is difficult, a simply hydraulic press in the lab could deliver hundreds of PSI.
- riffraff 5y ago
  I would be generous and assume this is a demo of something that is more relatable to normal people experiences, and they did actually test this with a hydraulic press in reality. It's a press release aimed at making the news, not a scholarly article, and those can be pretty.. misleading.
- dekhn 5y ago
  how does the inflation of the tire affect the mass load on the sample? are you saying if they changed the PSI of the car's tires they'd get different results (ignoring uninteresting details like how the PSI changed the tire geometry slightly?)
  - Ruthalas 5y ago
    The pressure to which the tire is inflated affects how much it spreads against the surface it sits on, changing the applied pressure.

rikkipitt 5y ago

Yep, also known as "corner weight" w.r.t. cars. Strange how they missed it. I wonder if it's a common misconception?

jve 5y ago

Plus if it was back of the car, it is more ligtweight. Moreover, that tire surface is much bigger and by part rests outside of material bounds.

dylan604 5y ago

Isn't an elephant's weight also distributed on 4 points of surface contact ("feet")?

aaron695 5y ago
That's what I thought, then I realised they took into account walking. The forelimbs also take more weight (60%) Foot pressure distributions during walking in African elephants https://royalsocietypublishing.org/doi/10.1098/rsos.160203 https://royalsocietypublishing.org/doi/10.1098/rsos.160203 Unlike a horse they never have all feet off the ground.

JKCalhoun 5y ago

Typical car tires are inflated to 35 PSI or so. There is a surprisingly large "footprint" from a tire supporting a car. I think the PSI in their test is fairly small. While I'm sure finding an elephant is difficult, a simply hydraulic press in the lab could deliver hundreds of PSI.

riffraff 5y ago
I would be generous and assume this is a demo of something that is more relatable to normal people experiences, and they did actually test this with a hydraulic press in reality. It's a press release aimed at making the news, not a scholarly article, and those can be pretty.. misleading.
dekhn 5y ago
how does the inflation of the tire affect the mass load on the sample? are you saying if they changed the PSI of the car's tires they'd get different results (ignoring uninteresting details like how the PSI changed the tire geometry slightly?)
- Ruthalas 5y ago
  The pressure to which the tire is inflated affects how much it spreads against the surface it sits on, changing the applied pressure.