2006-07-02 10:21:05 · 7 answers · asked by CLIVE K 1 in Science & Mathematics ➔ Chemistry
yes. hot air baloon replaces hot light air with heavy cold air, gets heavier and goes down.
2006-07-02 10:34:27 · answer #1 · answered by Anonymous · 0⤊ 0⤋
Releasing gas means that the overall mass of the balloon decreases, this however is not the reason for the subsequent loss of altitude, it's the loss of bouyancy due to the reduced volume of the gas envelope that counts.
As the pilot heats the air inside the balloon with the burner it expands increasing the overall volume and bouyancy and up she goes - when the air is released or allowed to cool it contracts, reducing the volume and bouyancy, and suddenly the ground starts getting larger !!
Rigid airships and dirigibles, which are essentially of a fixed volume work in a slightly different way. The ships contain closed bladders of helium and adjustable bladders of air which are inflated or deflated as required
Since air is heavier than helium the total mass of the airship increases for its volume and the ship goes down. Blowing out the air allows the helium to expand, reducing the mass of the airship for its volume and the ship goes up.
So in summary - Hot air balloons control the volume of the gas envelope and airships control total mass in order to change altitude.
2006-07-02 22:04:24 · answer #2 · answered by Anonymous · 0⤊ 0⤋
I'm a licensed balloon pilot and been flying for nearly the last 20 years... In most balloons we have a "vent" line we can pull that releases heated air out of the top of the envelope, it creates a vacuum and the heated air is replaced by cooler, more dense air. However, heat is gradually lost anyways, so we can also descend by simply not reheating the air already inside.
2006-07-07 16:28:51 · answer #3 · answered by Vakus 2 · 0⤊ 0⤋
do not confuse weight and mass. If you expel a gas you will lose mass, if the gas were lighter than air you could gain density if replaced by a gas heavier than air.
2006-07-02 10:42:12 · answer #4 · answered by mr.answerman 6 · 0⤊ 0⤋
By "buoyant" I assume you mean lighter than air at STP. If you, say, have compressed helium in a container and let it out, it will become lighter because the helium does actually weigh something.
2006-07-02 10:25:55 · answer #5 · answered by Dave R 6 · 0⤊ 0⤋
depends whether the gas is under pressure or released as a result of a chemical reaction. For example helium realeased from a pressurised steel cylinder will make the cylinder lighter.
2006-07-02 10:32:45 · answer #6 · answered by Robert A 5 · 0⤊ 0⤋
Yes.
2006-07-02 10:25:56 · answer #7 · answered by jimbo_thedude 4 · 0⤊ 0⤋