Is a pressurized air object heavier?

Unless you were driving a monster truck with REALLY big tires it wouldn't change the weight of your car by more than a pound, so it wouldn't really make a difference. Plus the helium would probably leak out of your tires more quickly.

For every cubic meter of air replaced with helium you get a whopping 2 or so pounds of lift. The average car probably has about 2-4 cubic meters of passenger and cargo space so again not a very appreciable gain there. Think about how large the Goodyear blimp needs to be to hold up that little passenger cabin.

seriously

not be a good

tweety bird on

lack of

The car would get lighter by the difference in weight between the car's volume in air and the car's volume in helium. That's not much.

Bob

Try again. Density of air at STP is 1.29 grams per liter.

ROTFLMAO

I forget why, but I have stuck in my head that an order-of-magnitude estimate for the lift of STP helium is around 1 pound per cubic yard, displacement.

Howzat? Doesn't the air (not to mention your cup of coffee and cellphone) go forward & to the right when you make a left turn? I'd think that the helium balloon would go to the back & left.

R, Tom Q.

Indirectly yes. When it is contained, but under less pressure it will take up more space, displacing more air and like a boat it will float.

Yea, it likely would be lighter (some uncertainty because I don't recall how helium acts under pressure, if it were to compress sufficiency more than air, it might not be lighter, but I really don't think that is an issue. However it might be a few ounces lighter, not enough to worry about.

Not even if you could create a perfect vacuum (which would be even lighter than helium. The car would still weigh far more than the air it displaces.

Empty is a relative term. A tankful of helium at

Of course if you release helium into a large balloon at some point it will lift the tank of compressed helium.

It's all about floating; floating in air is the same principle as floating in water. Basically if an object weighs less than surrounding gas or liquid weighs, it will float. For example as soon as the balloon inflates, it gets larger and displaces more air. As soon as the volume is large enough that the weight of air it displaces slightly exceeds the weight of the balloon, the internal helium gas, and everything attached to it, it will start to float.

Actually the primary factor after the weight of the tank and other equipment is the volume of air that the balloon displaces.

See, I just proved that nobody's perfect, not even me.

Jeff

Aha! Don't think that you're fooling anyone - I knew that that was your intention.

R, Tom Q.

Ask the guy in the lawn chair with the balloons and the bb-gun. He khnows all about how much helium is needed.

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The Myth Busters did that one and it took hundreds of very large balloons to lift a small child. You man in the lawn chair was proven a myth.

Add gas to an empty cylinder. The cylinder size is still the same, so there is no buoyancy difference in air (or indeed in water). Hence the only difference is yes it contains more mass (atoms), and therefore more weight as measured by a balance.

Compare with a baloon, there is a significan buoyancy difference of an empty baloon compared to a full one, and the net effect will be determined by the relative densities of the air (or gas) inside the baloon compared with the atmospheric gases.

Dean

I didn't see that show - what size balloons were they using? The references I've seen to Lawnchair Larry all say that he was using 40 + weather balloons. I don't know what size his balloons were, but it seems like 40 6-8' weather balloons would be plenty to lift an adult male.

R, Tom Q.

Wow. I certainly didn't know all these details. Thanks

He spent 110 dollars for the lawn chair. I assume it was made from aluminum. I didn't realize one could spend that much for an aluminum chair, but when you're going to 15,000 feet, it's worth the extra 95 dollars.

I didn't hear about this on the internet, which didn't exist then. I read it in the paper. I'm sorry thinkgs didn't turn out well for Larry. he had more imagination and courage than I do.

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I don't remember the size, but it was on Pilot #3 episode.

Absolutely, WRONG!

The answer is explained better by an understanding of basic physics of density, than doing a google search.

The tank is full of COMPRESSED helium. It's density per unit volume is much higher than the helium in a balloon. The balloon floats because of the differential of densities between AIR & HELIUM.

It is NOT the same scenario in the tyre, since we are dealing with the same gases, in the same reference frame. The tyre contains air at a higher density than the air in the frame of reference (around the tyre). Therefore it has MORE MASS when filled, than empty.

Yes, your friend is correct, and I guess he's interested in physics... - see my reply elsewhere in the topic.