Air All About Us - Exploring Science (1955)

[Music] it happened while David was making his bed it was just a little thing a feather that had come out of his pillow and floated to the floor what had it floated on air David had watched falling feathers before he knew he could keep one floating by blowing at it but he had never before thought about the air the feather floats on he began thinking about air air filled his lungs air filled his room he could feel it when he moved his hand [Music] around and [Music] Outdoors Outdoors air was everywhere he couldn't see it but he could see the things the air did and he knew it was everywhere there is air near the ground that we breathe there is air high up moving the [Music] Treetops and there is air higher than that higher than the highest trees higher than the highest clouds air is all around the earth like a great ocean and we are at the bottom of it air David's rear tire needed some air it was almost flat and that's what he was going to do this Saturday morning take his bike to The Filling Station to get air as he walked along David thought about air air weighs something everything does and the weight of all the air above us is pushing down on us all the time but air is all around us too does air only push down David remembered an experiment he once did in school with a balloon the balloon had holes in it that were covered with tapes in this experiment you put some powder into the balloon then you fasten a hose to the balloon from a tank of compressed air as more and more air goes in the balloon gets bigger and bigger now what is the air inside the balloon doing we can find out by pulling the tapes off one at a Time air must be pushing down on the bottom of the balloon because it's blowing the powder out well that isn't surprising but what will happen if we open the top hole powder is blowing out here too does that mean the air inside the balloon is also pushing up and what about the side hole more powder does that mean the air inside the balloon is pushing sideways too yes the air inside the balloon is pushing up and down and sideways in fact the air is pushing in all directions and air inside a balloon is just the same as the air all around us the air around us is pushing too how is the air pushing on David Air Above David is pushing down down on him air is also pushing on the front of David and on his back and on his sides and even down here underneath his feet where there are little bits of air the air is pushing up on David wherever the air is touching David it is pushing on him we call this pushing by the air air pressure wherever there is air there is air pressure rubber suction cups why do the suction cups stay on the board why are they so hard to get off is air pressure the answer when you just touch them to the board they don't stay you have to push them in hard and then they stay why what David knew about air pressure would help to explain it there is air all around the suction cup and there is air pressure pushing on the suction cup on all parts of it when you just touch the cup to the board you don't don't change the air pressure all around it but when you push it hard against the board you push most of the air out from underneath when you let the cup spring back there is less air under it than there was so there is less air pressure air pressure on the outside is pushing the cup against the board harder than the air pressure inside side is pushing it away so the outside air pressure keeps it on the board until you let some more air in under the cup David could see that suction cups work because of air pressure but are there other ways of using air pressure his tire uses air but does it use air pressure too let's find out from an air hose we can force air into the tire as more and more air goes in the tire becomes harder and harder why there is air pressure inside the tire the more air you force into the tire the greater the air pressure gets to to be finally the air inside is pushing so hard that the tire will hold up the bicycle and David to that's what enough air pressure can do does air pressure have anything to do with this automobile lift the lift is coming down and Air it's coming out here air stops coming out when the lift is all the way down how does the lift work opening the valve forces air into the lift and the lift goes up carrying the car with it David could see that air pressure can hold up the heavy car yes David was learning that air and air pressure have many uses on his way home he was reminded of another important use of air does air pressure help an airplane fly yes an airplane flies because of air pressure on its wings when the airplane is standing still there is air pressure all around the wings the air pressure pushes down just as hard as it pushes up but when the airplane starts moving forward the air pressure changes because of the way the wings are shaped as the plane goes faster there is less pressure pushing down than there is pushing up and when the plane is going very fast the air pressure pushing up lifts the heavy airplane that's why an airplane flies of course David didn't know all about that but he was going to learn because because he wanted to know more about air and air pressure and how we use it he was going to learn more about the ocean of air All About Us [Applause]