This is very misleading. Most of the discomfort would be from the hard table against the back of your hand, and this would be because of local pressure on specific points.
Pressure causes problems when there’s a big change in a relatively short time. Ears, for example, have a hard time with this, but you can equalize them by closing your nose and mouth and trying to blow out. Before I knew about this trick, I could never dive to the bottom of the pool. Now, no problem.
A more realistic example would be to bury your hand in a foot or two of fine sand. Does that sound uncomfortable?
In the sand example, it’s also important that the pressure is acting from all sides (top, bottom, left, right) so there’s no force acting to deform your hand.
We can handle a relatively large range of pressures, and there are other problems before you start causing mechanical damage from the actual pressure (lack of oxygen at low pressure, dissolved gas at high pressure).
This is very misleading. Most of the discomfort would be from the hard table against the back of your hand, and this would be because of local pressure on specific points.
Good point, but it feels about as uncomfortable if you use a padding over the table that eliminates the stress concentrations at your bones and knuckles. Especially if you double the dumbbell weight and recognize that it’s only a pressure increase of 10%.
Your thought experiment with the dumbbell is an incorrect way of thinking about ambient pressure. Ambient pressure pushes against an object from every direction. It does not work to deform or break, only compress from all sides.
Picture this: You have a hand-sized water balloon on a table. You place the two dumbbells on it; it breaks. You have another water balloon. You take this one, tie it to a dumbbell, and drop it into deep water. Do you expect it to break when descends to 3 feet (i.e. 10% increase in pressure)?
I would not expect it to break at all. When water and other non-gases are put under pressure, the bonds and repulsive forces within push back.
Don’t quote me on this part, but I would guess that to break a bone with just ambient pressure, you’d have to raise the pressure to about the compressive strength of the bone, around 100 megapascals. For reference, standard atmospheric pressure is around 100 kilopascals.
edit: changed 3 meters to 3 feet, per prase’s comment.
This is very misleading. Most of the discomfort would be from the hard table against the back of your hand, and this would be because of local pressure on specific points.
Pressure causes problems when there’s a big change in a relatively short time. Ears, for example, have a hard time with this, but you can equalize them by closing your nose and mouth and trying to blow out. Before I knew about this trick, I could never dive to the bottom of the pool. Now, no problem.
A more realistic example would be to bury your hand in a foot or two of fine sand. Does that sound uncomfortable?
In the sand example, it’s also important that the pressure is acting from all sides (top, bottom, left, right) so there’s no force acting to deform your hand.
We can handle a relatively large range of pressures, and there are other problems before you start causing mechanical damage from the actual pressure (lack of oxygen at low pressure, dissolved gas at high pressure).
edit: grammar
Good point, but it feels about as uncomfortable if you use a padding over the table that eliminates the stress concentrations at your bones and knuckles. Especially if you double the dumbbell weight and recognize that it’s only a pressure increase of 10%.
I don’t agree with this.
Your thought experiment with the dumbbell is an incorrect way of thinking about ambient pressure. Ambient pressure pushes against an object from every direction. It does not work to deform or break, only compress from all sides.
Picture this: You have a hand-sized water balloon on a table. You place the two dumbbells on it; it breaks. You have another water balloon. You take this one, tie it to a dumbbell, and drop it into deep water. Do you expect it to break when descends to 3 feet (i.e. 10% increase in pressure)?
I would not expect it to break at all. When water and other non-gases are put under pressure, the bonds and repulsive forces within push back.
Don’t quote me on this part, but I would guess that to break a bone with just ambient pressure, you’d have to raise the pressure to about the compressive strength of the bone, around 100 megapascals. For reference, standard atmospheric pressure is around 100 kilopascals.
edit: changed 3 meters to 3 feet, per prase’s comment.
3 meters underwater is about 30% of atmospheric pressure added, not mere 10%.
Sorry, I forgot feet != meters. Ha.