A good test would be to take a tank of compressed air. Weigh it while it's empty, and then fill it up to 100 psi and weigh it again. The tank is rigid, so you don't have to worry about bouyancy being a concern, since the tank stays the same size.
The compressed air canister will work, but the ballon will not.
Scales measure weight, not mass. A change of bouyancy will skew the results if you're using a scale. You can put me on a scale, and put the Goodyear Blimp on a scale. The blimp will weigh less than I do, although it is much more massive.
You'd have to weigh both in a vacuum to get accurate results.
Like I said to the other poster, using a scale to measure mass is not a good idea. Scales measure weight, not mass. If you take that same balloon with the air from your lungs in it, and warm it up, its weight is going to change. Its mass will not.
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.
911paramedic
Diamond Member
- Jan 7, 2002
- 9,448
- 1
- 76
Go to your local scuba store.
Ask to feel the weight of a filled tank and one that isn't. There is an obvious weight difference.
BTW, how does your friend think a barometer works? Pressure at sea level and all that...
Ask to feel the weight of a filled tank and one that isn't. There is an obvious weight difference.
BTW, how does your friend think a barometer works? Pressure at sea level and all that...
True. The helium baloon goes up because gravity acting on helium (down) is less than the boyant force of the air (up). Using this same law of physics, blowing up a baloon will show it has the same weight as an empty baloon because the gravity acting on the air (down) is the same as the boyant force of the air (acting up). Blowing up a baloon with air will not show air has mass.
air has mass because gravity pulls it down, if it didn't have mass, our air (atmosphere) would leave the earth
Jeff7
Lifer
- Jan 4, 2001
- 41,596
- 19
- 81
12g CO2 cartridge. Weigh it.
Let the air out of it somehow. It is under a helluva lot of pressure though.
Weight it again.
Other fun thing to do:
Get a stick like a meter stick, something you can break. Set it on a table with several inches of it hanging over the edge of the table. Lay out a sheet of newspaper over the rest of the stick. Slam your fist onto the overhanging portion of the stick. It should break off, as it was unable to lift the light paper because of all that heavy air over top of it..
Let the air out of it somehow. It is under a helluva lot of pressure though.
Weight it again.
Other fun thing to do:
Get a stick like a meter stick, something you can break. Set it on a table with several inches of it hanging over the edge of the table. Lay out a sheet of newspaper over the rest of the stick. Slam your fist onto the overhanging portion of the stick. It should break off, as it was unable to lift the light paper because of all that heavy air over top of it..
The whole idea behind the buoyant force is that the resulting force is equal to the mass of displaced substance (air in this case).
Put yourself in an air tight room with 2 empty baloons and blow one up USING YOURLUNGS. Now no new air has entered the room and no air has left the room. You have not displaced the air because you mearly transfured it from the room into the baloon. You have compressed it slightly and that will make the molecules in the room farther appart than before but that is negligable (you will see why in a second). Now weigh the empty baloon. You will see it weighs X (X is the weight of the baloon). Now weigh the filled baloon. You will find it weighs X+A (where A is the mass of the air in the baloon). The reason this is, is because gravity is acting on the baloon and the air.
When you add the air to the baloon you can think of it as one system and not air + baloon. When the mass is measured it will measure the mass of the empty baloon + the mass of the air inside of it.
Now why is that change in distance between molecules not taken into account? Imagine a bigger room now. One bigger than the earth. Now is that tiny tiny tiny shift going to even be noticable? Nopers.
Youre argument of the buoyant force canceling out the gravational force here is moot.
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. Edit: We must also bring into play the idea that each action has an equal and opposite reaction.
Oh, and the balance idea was indeed flawed because the volume of the balloon changes in addition to the mass, thus bringing density into play and complicating things. Still works, but has a more complicated explanation.
Oh, and the balance idea was indeed flawed because the volume of the balloon changes in addition to the mass, thus bringing density into play and complicating things. Still works, but has a more complicated explanation.
Fenixgoon
Lifer
- Jun 30, 2003
- 32,883
- 12,165
- 136
light something on fire - the reaction occurs because oxygen fuels the fire.
for the lab - take a strip of magnesium and put it in a crucible, then heat the crucible with a burner. the magnesium will react to form MgO, and gain mass. weigh the magnesium before/after reaction.
for the lab - take a strip of magnesium and put it in a crucible, then heat the crucible with a burner. the magnesium will react to form MgO, and gain mass. weigh the magnesium before/after reaction.
911paramedic
Diamond Member
- Jan 7, 2002
- 9,448
- 1
- 76
Air is mostly nitrogen and oxygen, those have mass don't they?
Your friend, on the other hand, is dense. THAT is a fact.
Your friend, on the other hand, is dense. THAT is a fact.
911paramedic
Diamond Member
- Jan 7, 2002
- 9,448
- 1
- 76
DrPizza
Administrator Elite Member Goat Whisperer
he'd be hard pressed to notice the difference, unless the balance was in a vacuum.
To understand why - how heavy is a water balloon - when it's weighed underwater? - the weight of the latex part of the balloon. There is a slight difference though in the case of air as the air inside is under *slightly* more than atmospheric pressure; not enough to notice though.
DrPizza
Administrator Elite Member Goat Whisperer
probably the best way (and a couple people suggested it)
Here's another - use Newton's laws. F=m*a - If it takes a force to accelerate air, then it has mass.
Blow up a balloon. Since the balloon is blown up, the air MASS is pressing against the sides. If air didn't have any mass, you wouldn't be able to blow up the balloon at all.
Amused
Elite Member
- Apr 14, 2001
- 57,055
- 18,410
- 146
here is an easy one.
F=ma
take a pencil on a table and blow it from one side to the other.
visually you can see that a>0 and f>0 because it is moving. thus m has to be > 0.
you can also explain it as the force > 0 because it is moving. this means that a must be > 0 and m must be > 0.
F=ma
take a pencil on a table and blow it from one side to the other.
visually you can see that a>0 and f>0 because it is moving. thus m has to be > 0.
you can also explain it as the force > 0 because it is moving. this means that a must be > 0 and m must be > 0.
TRENDING THREADS
-
Discussion Zen 5 Speculation (EPYC Turin and Strix Point/Granite Ridge - Ryzen 9000)- Started by DisEnchantment
- Replies: 24K
-
Discussion Intel Meteor, Arrow, Lunar & Panther Lakes Discussion Threads
- Started by Tigerick
- Replies: 20K
-
-
-
Facebook
Twitter