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Post by rmc on Apr 23, 2022 20:41:24 GMT
This question is part of Conservation of Energy.
A hammer strikes an anvil with momentum p in an atmospheric pressure one atmosphere. Part of the energy is transferred to the anvil, while another part is transferred to the atmosphere.
Another hammer strikes an Anvil also with momentum p, but this time there is no atmosphere.
Would the energy that would have gone through the atmosphere, had there been one, now go to the anvil?
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Post by GTCGreg on Apr 23, 2022 23:49:22 GMT
This question is part of Conservation of Energy. A hammer strikes an anvil with momentum p in an atmospheric pressure one atmosphere. Part of the energy is transferred to the anvil, while another part is transferred to the atmosphere. Another hammer strikes an Anvil also with momentum p, but this time there is no atmosphere. Would the energy that would have gone through the atmosphere, had there been one, now go to the anvil? I don't know if I'm understanding this right, but in the first example, how is energy being transferred into the atmosphere? The only way I can see is if there is some heat generated by the resistance of the air as the hammer moves through it. This would slow down the hammer a little so less energy would be transferred to the anvil. With no atmosphere, the hammer would not be slowed down so more energy would go to the anvil. |
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Post by the light works on Apr 24, 2022 0:41:27 GMT
it is a logical conclusion, but the specifics are way above my pay grade.
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Post by rmc on Apr 24, 2022 13:02:29 GMT
This question is part of Conservation of Energy. A hammer strikes an anvil with momentum p in an atmospheric pressure one atmosphere. Part of the energy is transferred to the anvil, while another part is transferred to the atmosphere. Another hammer strikes an Anvil also with momentum p, but this time there is no atmosphere. Would the energy that would have gone through the atmosphere, had there been one, now go to the anvil? I don't know if I'm understanding this right, but in the first example, how is energy being transferred into the atmosphere? The only way I can see is if there is some heat generated by the resistance of the air as the hammer moves through it. This would slow down the hammer a little so less energy would be transferred to the anvil. With no atmosphere, the hammer would not be slowed down so more energy would go to the anvil. Sound in atmosphere upon impact. No sound in vacuum. That's the energy going into atmosphere that I was referring to. But, drag type friction also causes energy loss to atmosphere too, as you say. In vacuum, no drag. For the strike at Anvil to have same momentum p, then the speed in atmosphere at Anvil strike is made to be the same as Anvil strike in vacuum. So, overcame what drag there was to get same speed at strike. (and same mass m for each hammer head, by the way) The energy at Anvil strike is the question, though. If no atmosphere, does energy that would have been sound, now go into anvil? |
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Post by GTCGreg on Apr 24, 2022 16:08:16 GMT
I don't know if I'm understanding this right, but in the first example, how is energy being transferred into the atmosphere? The only way I can see is if there is some heat generated by the resistance of the air as the hammer moves through it. This would slow down the hammer a little so less energy would be transferred to the anvil. With no atmosphere, the hammer would not be slowed down so more energy would go to the anvil. Sound in atmosphere upon impact. No sound in vacuum. That's the energy going into atmosphere that I was referring to. But, drag type friction also causes energy loss to atmosphere too, as you say. In vacuum, no drag. For the strike at Anvil to have same momentum p, then the speed in atmosphere at Anvil strike is made to be the same as Anvil strike in vacuum. So, overcame what drag there was to get same speed at strike. (and same mass m for each hammer head, by the way) The energy at Anvil strike is the question, though. If no atmosphere, does energy that would have been sound, now go into anvil? In that case, the sound would be created by the anvil vibrating after it was struck. The air would help dampen that vibration until the ringing eventually stopped with some of the energy transferring to the air. With no air, the vibration would still eventually dampen out but the energy caused by the vibrations would remain in the anvil as heat. So I'd guess that yes, without air, the anvil would retain more energy than with air present. We are probably talking about very small quantities here. Just about all the energy transferred to the anvil is going to end up heating the anvil. This thermal energy is going to eventually be removed from the anvil either by convection with the air or through radiation. With no air, the thermal energy in the anvil will still eventually be lost, but it will take a little longer because now it's all being lost just through radiation. This is all just guessing on my part. Don't take any of it to the bank. |
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Post by the light works on Apr 25, 2022 2:22:57 GMT
I suppose one way to test it, would be to make a trip hammer that could work inside a vacuum chamber. let one bang away in normal atmosphere and one in a vacuum, and use a thermal imager to compare the heat buildup in the anvil. I guess some sort of piezo device to measure the imapact, as well. rpobably have to switch devices in the vacuum chamber at some point, to get truly relevant numbers.
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Post by rmc on Apr 27, 2022 9:29:49 GMT
I suppose one way to test it, would be to make a trip hammer that could work inside a vacuum chamber. let one bang away in normal atmosphere and one in a vacuum, and use a thermal imager to compare the heat buildup in the anvil. I guess some sort of piezo device to measure the imapact, as well. rpobably have to switch devices in the vacuum chamber at some point, to get truly relevant numbers. Momentum on each needs to be the same, the masses the same, and so on. Since momentum is velocity multiplied against mass, the hammer in air needs to overcome slight air drag and get up to same speed as vaccum hammer. Having them near each other and in synchronous motion might do it, but to get them in sync means the air environment hammer needs some slight push. Whereas the vacuum hammer can be dropped freely, but raised under power. |
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Post by wvengineer on Apr 27, 2022 12:36:30 GMT
Sum of the energy entering a system is equal to the some of the energy leaving the system.
You will have roughly the same amount of vibration energy in the system after the hammer strike in air vs in vacuum. That energy has two places to go. Either into the air or into the anvil's mount/earth. I would see the air would act as a dampening effect on the anvil's vibration. Air absorbs some of the vibration, helping to reduce the amount of energy in the anvil. Without the air to absorb the energy, it would all have to go into the mount.
In all practicality, I would expect the amount of vibration energy that goes into the air to be small compared to the energy going into the mount. In a vacuum, the anvil will vibrate for a bit longer, but not much. However, that is just my gut reaction. I have not done any calculations on this.
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Post by the light works on Apr 27, 2022 15:51:11 GMT
I suppose one way to test it, would be to make a trip hammer that could work inside a vacuum chamber. let one bang away in normal atmosphere and one in a vacuum, and use a thermal imager to compare the heat buildup in the anvil. I guess some sort of piezo device to measure the imapact, as well. rpobably have to switch devices in the vacuum chamber at some point, to get truly relevant numbers. Momentum on each needs to be the same, the masses the same, and so on. Since momentum is velocity multiplied against mass, the hammer in air needs to overcome slight air drag and get up to same speed as vaccum hammer. Having them near each other and in synchronous motion might do it, but to get them in sync means the air environment hammer needs some slight push. Whereas the vacuum hammer can be dropped freely, but raised under power. if you wanted your initial impact to be the same, you'd use your piezo device to tune the trip hammers to strike with the same force, by adjusting the weight of the hammerhead. then you could adjust the rate of the trip to get the same strike rate in each test. at which point, you would only need to make one hammer rather than doing tests with each to account for slight variables in the hammers, since your piezo device was recording that your strikes were uniform in force and rate. you might be starting to get into the realm of "if you make two machines that give exactly the same results, are they different?" though. |
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Post by GTCGreg on Apr 28, 2022 0:30:47 GMT
To eliminate variables, it would be better to use just one machine that can either be operated in air or in a vacuum. Then use either an impact sensor, like TLW suggests, or a laser to measure and adjust the speed of the hammer to compensate for air resistance. The numbers you are looking at are going to be so small that they are almost impossible to measure anyway. The last thing you need is possible variations between two different test apparatuses.
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