2007-05-15 13:41:11 · 7 answers · asked by Anonymous in Science & Mathematics ➔ Physics
helium is ligther than air that's why.
2007-05-15 13:48:08 · answer #1 · answered by Anonymous · 0⤊ 0⤋
jsard got it right by assuming that 'it' in your question refers to the helium in the balloon, not the ambient air around it. In the latter case, the answer is reversed; the balloon will sink when 'it' is warm (air less dense) and vice-versa........
In any event, the delta T between the helium & the air will always be seeking zero as a value, so the condition you stipulate will be very transient.
2007-05-15 14:30:08 · answer #2 · answered by Steve 7 · 0⤊ 0⤋
when temperature increases, so does the pressure and volume. the helium atoms will bounce off the sides of the balloon more often and be more spread out,allowing the balloon to float. When you decrease the temperature, you're decreasing the pressure which means the atoms are not spread as far apart, making the balloon heavier and fall
2007-05-15 14:35:45 · answer #3 · answered by anonymous 1 · 0⤊ 0⤋
Does it really fall when its cold? I never knew that...it should rise just because Helium is lighter in weight than air...
But I suppose it could be because hot air rises and cool air falls (because of the speed of the particles)
2007-05-15 13:46:30 · answer #4 · answered by smokefanTS20 3 · 0⤊ 0⤋
The helium expands when it is warm increasing the amount of air that it displaces. Since the buoyant force is equal to the weight of the displaced air, the greater buoyant force is able to overcome the weight of the balloon(and contents).
2007-05-15 13:51:31 · answer #5 · answered by jsardi56 7 · 0⤊ 0⤋
It doesn't. Helium is so much lighter than air that even when cold it will still rise.
2007-05-15 15:25:28 · answer #6 · answered by Norrie 7 · 0⤊ 0⤋
Simple: Hot = expand; Cold = Contract
2007-05-15 13:46:53 · answer #7 · answered by jnmwizkid1 2 · 0⤊ 0⤋