Gravity and Density

If I had a balloon full of gas, and inside that balloon a solid canister that had a much smaller volume than the balloon but could hold all the gas inside the balloon under pressure, would there be a (detectable or theoretical) change in the gravity generated by forcing all the gas into the canister under pressure?

Yes, due to the potential energy created, but it would be negligable. However, it would change the bouyancy of the gas, due to the reduction in volume, so the net force on the gas would change.

Would I be able to detect this change with an accelerometer placed immediately above the balloon?

phinds
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Would I be able to detect this change with an accelerometer placed immediately above the balloon?

What is it that the accelerometer would be measuring?

The acceleration towards a point, in this case it would be both the earth and the compressed gas (due to its heightened gravitational pull (I'm not for a second saying it would be a big gravitational pull, I'm just interested in measuring it))

phinds
Gold Member
2021 Award
The acceleration towards a point, in this case it would be both the earth and the compressed gas (due to its heightened gravitational pull (I'm not for a second saying it would be a big gravitational pull, I'm just interested in measuring it))

If I correctly understand what your saying, then no I don't see how there would be any difference UNLESS the accelerometer moved closer to the center of mass of the gas, since that would cause a tiny increase in the gravity measured by the accelerometer (the amount would not be measurable with anything like today's technology but it would exist)

Is there any way I can create a change in gravity that I could monitor with DIY lab equipment?

phinds
Gold Member
2021 Award
Is there any way I can create a change in gravity that I could monitor with DIY lab equipment?

I don't have any answer for that but I'll bet some of the more clever folks here will.

Matterwave
Gold Member
Is there any way I can create a change in gravity that I could monitor with DIY lab equipment?

You have to define what you mean by "change in gravity". If you mean change in the gravitational force felt by some object, then...yes...it's very easy, you just change the mass of that object (cut off a piece of it), the gravitational force will reduce. Take a piece of putty and weigh it, and then cut off a piece and weigh it again, the lower reading shows a reduction in the gravitational force....

But I suspect this is not what you mean.

phinds
Gold Member
2021 Award
But I suspect this is not what you mean.

Right ... I was going to suggest that he eat a Big Mac and then reweigh himself, but I came to the same conclusion that you did so bit my tongue.

I want to detect a change without touching the object (for example, an accelerometer dangling above an object)

phinds
Gold Member
2021 Award
I don't think you'll be able to do that w/ DIY equipment because the change will be very subtle almost whatEVER you do, relative to the gravity of the earth, which you can't remove from the experiment.

For example, I believe that the discovery and mapping of mascons in the earth required very sensitive instruments and you are NOT going to come close to producing a mascon.

Ibix