Most children of school age who wet the bed at night have what doctors term primary enuresis.. They have never had nighttime control of their bladder. Family history plays a role, too, in incontinence in children. If you wet the bed as a child, don't be surprised when your child does, too.
One thing to notice is that if you put a gallon of air on a scale, (in a wieghtless container, of course) you would measure zero, exactly. That's because the buoyancy caused by the surrounding air exactly counteracts the weight of the air in the container. If you pressurized the air in your gallon container to, say ten times the outside pressure (or 147.0 psi absolute, or 132.3 psi gauge) it would now weigh nine times 0.01, or 0.09 lb.
First, we have to understand how pressure is measured. If we were to take a one inch column of air all the way up through the atmosphere, it would weigh 14.7 pounds. For this reason, we like to say that the standard air pressure (at sea level) is 14.7 pounds per square inch (psi). Water weighs more than this, though. Each one inch column thatâs one foot deep will weigh 0.445 pounds.