What is the maximum altitude of a hot air balloon?
Is it dangerous to ride in a hot air balloon? They look fun & romantic, but I've always thought a hot air balloon would be a little scary.
The manufacturer had added an extra propane tank to the balloon, but the operator chose to fly it, even though it was unsafe. Who is most responsible?
ok I guess hot water is lighter than cold water but what about hot air and cold air?
we can breathe cold air but not hot air so how does that work? is it because hot air is heavier than cold air? and if you put the covers over your head you can't stay ...
how do I ride my boyfriend?
What is air pollution?
How to ride a skateboard?
What is air's weight?