Air pressure Definition and 207 Threads

I'm building a hovercraft, and I am using an old computer fan to blow air into a plastic garbage bag and fill it up. I need to poke a few holes on the bottom of the garbage bag to let the air out, and I want to have a less friction as possible. What size should the holes be? And how many?

I vaguely remember a physics teacher once telling me that it is impossible to suck water through a straw that is longer than 32 feet because the air preassure is not strong enough to push it that high when you create a vacuum in your mouth. I know the mechanics behind sucking water through a...

Hi All, I've come across something that surprised me but I'm sure has a logical explanation... I have a two small ID tubes that have exactly equal impedance to air flow (for the purposes of the discussion the flow is 2ml/min). I connect them in series with one end of the system exposed...

Higher the temperature, lower is the air pressure. Lower the temperature, higher is the air pressure. Are they right? If yes, why? :confused:

what is the optimum air pressure for sound waves? is there a graph that i can look at that ranges from 0 bar (or whatever it's measured in) to such high pressure that the air is almost a solid. what would you measure the flow of sound waves in?

Alright, this might be a dumb question.. my friend and I are in a little debate. I have built two kinds of "potato cannons": one uses the force of a acetelyne gas + oxygen reaction for the energy (single explosion, flings it far). The other uses actual compressed air: I would pump air into a...

The air temperature at an altitude of 10,000 meters is a chilling -35º C. Cabin temperatures in airplanes flying at this altitude are comfortable because of air conditioners rather than heaters. A.) Find the pressure at 10,000 m and B) Find the temperature of the air before the air...