Prove that air has mass

[Summitdrinker]

Originally posted by: Elderly Newt

Originally posted by: Summitdrinker
air has mass becuase gravity pulls it down, if it didn't have mass, our air (atmophere) would leave the earth

No, air has mass because it's matter. Air has weight because of gravity.

I thought gravity pulls mass not weight

gravity is force of attraction on bodies of mass??I'm I correct

 

[Howard]

Gravity gives mass a weight, which is a force. Mass and force are quite different.

 

[WildHorse]

a) air pressure proves that air has mass, since gravity pulling the mass of air creates the pressure. Gravity acts on MASS. Air pressure exists. Thus, air has mass.

So just do an experiment demonstrating existence of air pressure. Details are left for the student to work out.

b) Flashlight beam diffusion is caused by massive particles in the air. So it's the old " shine a flashlight in the cardboard box " drill.

 

[MrPickins]

Originally posted by: her209

Originally posted by: newmachineoverlord
Y'all are overthinking this. Just take one balloon, blow it up, don't tie it, set it down on table. F=MA, so if the air in the balloon provides enough thrust as it escapes to move the balloon, it MUST have mass.

That proof doesn't work in space.

Unless I'm mistaken, that principle is how all rockets operate, and it works well in space.

IMO, this is the easiest proof.

 

[Suspicious-Teach8788]

Originally posted by: keeleysam

Originally posted by: Summitdrinker
but the air in the inflated ballon is compressed air

You can't compress nothing.

It's not compressed. The pressure inside = pressure outside otherwise you're not at equilibrium.

 

[Suspicious-Teach8788]

Originally posted by: her209

Originally posted by: newmachineoverlord
Y'all are overthinking this. Just take one balloon, blow it up, don't tie it, set it down on table. F=MA, so if the air in the balloon provides enough thrust as it escapes to move the balloon, it MUST have mass.

That proof doesn't work in space.

Actually it does, and this is not F = ma, you're talking about momentum. m1v1 = m2v2. How do you think a rocket works?

Gasses are expelled backwards from the engine and thus the rocket moves forward because momentum must be conserved. Simple.

 

[TheoPetro]

Originally posted by: DLeRium

Originally posted by: keeleysam

Originally posted by: Summitdrinker
but the air in the inflated ballon is compressed air

You can't compress nothing.

It's not compressed. The pressure inside = pressure outside otherwise you're not at equilibrium.

theres an inward restoring force because of the baloon. The psi outside != the psi inside.

 

[mercanucaribe]

Originally posted by: AbAbber2k

Originally posted by: Summitdrinker
but the air in the inflated ballon is compressed air

It doesnt matter. :disgust:

The fact that the air in the inflated balloon is compressed is the only reason it goes lower. If the air was the same density as the surrounding atmosphere, its mass would be balanced exactly by the atmosphere. Ever heard of bouyancy???

 

[everman]

Normally I say that there aren't any stupid questions, but I'll make an exception for this one. Unless you are in the third grade that is.

 

[blueshoe]

Originally posted by: JRich
Have him prove that light has mass

Just take two baloons and fill one up with light and take the masses of each one. Duh!

 

[Eeezee]

"Proof that air has mass?"

Air has pressure

/thread

 

[Rubycon]

Why is it that elementary physics and mathematics posts have the most responses? (outside of the typical YAGT that survives padlocking into archival oblivion! )

If someone can come up with a spreadsheet revealing the predatory results of their cat surely someone can do this with these posts.

 

[Eeezee]

Originally posted by: her209

Originally posted by: newmachineoverlord
Y'all are overthinking this. Just take one balloon, blow it up, don't tie it, set it down on table. F=MA, so if the air in the balloon provides enough thrust as it escapes to move the balloon, it MUST have mass.

That proof doesn't work in space.

Why wouldn't it work in space?

Unless you mean you're floating in space and don't have any air in your lungs with which to blow up the balloon.

 

[bonkers325]

Originally posted by: iliopsoas
What's a simple experiment to prove that air has mass? It only has to be qualitative, not quantitative.

A friend asked me this and I couldn't come up with anything It's been too long since the old physics days.

put a balloon in water, it will sink. fill it up with air, and it will float.

why? because air is less dense than water. since now u know air has density, you can prove it has mass because density = mass / volume

 

[bonkers325]

double post!

 

[amol]

Originally posted by: bonkers325

Originally posted by: iliopsoas
What's a simple experiment to prove that air has mass? It only has to be qualitative, not quantitative.

A friend asked me this and I couldn't come up with anything It's been too long since the old physics days.

put a balloon in water, it will sink. fill it up with air, and it will float.

why? because air is less dense than water. since now u know air has density, you can prove it has mass because density = mass / volume

that works even if mass = 0

 

[Slew Foot]

What we did in school was to take a styrofoam cup and stuff the bottom with paper towels. Turn it upside down into a tank of water for a second and then take it out. Since ari takes up space, the paper comes out dry. Not sure if that's what you were looking for but back in 2nd grade I remember doing that experiment.

 

[iliopsoas]

Originally posted by: h8red
Weigh a canister of compressed air. Remove air from canister. Weigh empty canister. Or do it with a balloon as said before

The difference in weight (between a full canister and an empty canister) is probably negligible and would not be detected by any old scale. Correct me if I'm wrong.

 

[iliopsoas]

Originally posted by: 91TTZ

Originally posted by: TheoPetro
are you kidding?

well heres your homework help from me. take 2 baloons. Blow one up. set the deflated one on one side of a balance and set the inflated one on the other side.

That is not a good test at all.

Helium has mass, but if you did your test and compared the helium-filled balloon to the deflated balloon, the helium balloon would be lighter. The test would erroneously "prove" that the "nothing" in the deflated balloon has more mass than the balloon filled with helium.

Your test tests bouyancy, not mass.

Yup, that's what I figured. It tests density, I think

 

[her209]

Originally posted by: Eeezee

Originally posted by: her209

Originally posted by: newmachineoverlord
Y'all are overthinking this. Just take one balloon, blow it up, don't tie it, set it down on table. F=MA, so if the air in the balloon provides enough thrust as it escapes to move the balloon, it MUST have mass.

That proof doesn't work in space.

Why wouldn't it work in space?

Unless you mean you're floating in space and don't have any air in your lungs with which to blow up the balloon.

It wouldn't work in space because the air escaping out of the balloon does not have anything to push against, i.e., no thrust.

 

[tyler811]

Originally posted by: TheoPetro

Originally posted by: MS Dawn
You could take a field trip to Washington D.C. if your experiment involves copious amounts of hot air. :laugh:

why go that far when P&N is just one floor down?

ftw

 

[iliopsoas]

Originally posted by: Fritzo

Originally posted by: 91TTZ

Originally posted by: patentman

Originally posted by: iliopsoas

Originally posted by: TheoPetro
are you kidding?

well heres your homework help from me. take 2 baloons. Blow one up. set the deflated one on one side of a balance and set the inflated one on the other side.

Ahhh. I thought of that. But how do you ensure that both balloons weigh the same? And wouldn't this just test density and not necessarily mass?

Easiest way to show is has mass is with a revision of the above suggested experiment, and it will take into acocunt the possible differences in mass between the two ballons.

Basically you need to make a makeshift balance with a piece of string attached the cented of a rod. At each end of the rod, attach a string, tie the ends of each string at the ends of the rod to 1 balloon each (deflated). Hang the balance by the center string. Look at where each balloon hangs (you can take markings if you want to be a little more scientific). After you've made a note of where the uninflated balloons are hanging, fill one of the balloons with air, but leave the other deflated. Re-hang the balance in the same place. The one with air in it should hang lower than marking for the balloon where it did whilst uninflated, thus proving that air has mass.

Nope.

That experiment will not work. You cannot use a scale or a balance to measure mass when bouyancy is a factor.

If you conducted this experiment in a vacuum, it will work. In air, it will not work. I already pointed out why it won't work in air- you could fill the balloon with a substance less dense than air, and although you added mass, your test would show that the mass has decreased.

Let's run your experiment too see how it works- we compare an empty balloon to one filled with an unknown gas. To see if that gas has mass, we put them on your balance. Depending on the mixture of gases, the filled ballon might hang lower than the empty balloon (making it appear to have more mass than the empty balloon), it might appear to be exactly the same weight (meaning it has the same mass), or it might float higher(meaning it has less mass). In reality, in all three cases we added mass compared to the empty balloon, but your experiment would deliver three different results.

Bouyancy is not a factor here...he's not filling the ballon with helium.

I'm not filling the balloon with helium. But the experiment should be valid for whichever gas I choose, should it not? If the experiment does not hold true for different gases, then it is a design flaw.

 

[iliopsoas]

Originally posted by: everman
Normally I say that there aren't any stupid questions, but I'll make an exception for this one. Unless you are in the third grade that is.

It may be stupid to you but it's pretty darn obvious you can't come up with simple explanation for this concept to teach a bunch of fourth-graders.

 

[AaronB]

Originally posted by: her209

Originally posted by: Eeezee

Originally posted by: her209

Originally posted by: newmachineoverlord
Y'all are overthinking this. Just take one balloon, blow it up, don't tie it, set it down on table. F=MA, so if the air in the balloon provides enough thrust as it escapes to move the balloon, it MUST have mass.

That proof doesn't work in space.

Why wouldn't it work in space?

Unless you mean you're floating in space and don't have any air in your lungs with which to blow up the balloon.

It wouldn't work in space because the air escaping out of the balloon does not have anything to push against, i.e., no thrust.

That's not how it works.

 

[Brutuskend]

If something is lighter than air (helium as an example) is has less mass right?

Or am I off base here?