Wonder World Of Science : Why Don't I Fall Up?

[Music] uhoh I wonder I wonder what do you wonder wondercat I wonder why don't I fall up why don't you fall up well if you're curious enough you can find out just to get started let's agree on which way is up that's easy that way is up that bird is flying up and that plane it's going up too so up is that way you know away from the ground or you could say away from the earth right right and down which way is that down that's toward the ground toward the Earth right right so when you say that something Falls or moves up or down you're really describing the direction it's moving that's right toward or away from the earth but I still don't know why I fall down instead of up well look around look at the things that move and see if you find some Clues as to why those things move in One Direction instead of in the opposite Direction well I'm looking at things that are moving but I haven't found any clues [Music] yet hey look at that ball it isn't moving at all well keep on looking and maybe you'll find out why oh I see why the ball isn't moving it's in the middle of a rope that both sides are pulling on in a tug of war it looks like one side is pulling just as hard as the other side side is what do you think would have to happen for the ball to move one side would have to start pulling harder and I think that's what's going to happen now but when the ball moves which way will it move toward the side that's pulling harder yes things start to move when they are pulled or pushed in One Direction harder than in another so I guess I understand the reason I fall down and don't fall up there must be something pulling me down toward the ground and it must be something that pulls me down harder than anything that pulls or pushes me up very good but I wonder what do you wonder wondercat I wonder what is it that's pulling me [Music] down I know what was pulling on the ball in the tug of war when one team pulled harder than the other team team did the ball moved it moved in the direction of the harder pull but what pulls things that makes them fall down well remember things fall toward the earth does that mean that the Earth pulls things down that's right and we give a name to the pull of the earth we call it [Music] gravity gravity I'll try to remember that word but I wonder I could see the hands of the people pulling on the rope and moving the ball but I don't think I've ever seen the Earth pulling on anything that's because the Earth can pull on things without touching them you can't see gravity but you can see things move because gravity pulls them toward the Earth gravity is pulling you too right now but I'm not falling why remember remember why the ball didn't move at first in the tug of war well both sides were pulling on the rope but one pull wasn't stronger than the other say since I know that gravity is pulling me down but I'm not moving something else must be pulling me up just as hard right yes but not pulling pushing up on you in order for the branch to hold you up it has to push you up just as hard as gravity is pulling you down if it didn't I'd fall down I see what you mean the small branches on a tree aren't very strong that bird should be careful well gravity doesn't pull down as hard on that bird as it pulls down on you it doesn't how hard does it pull down on us well you can find out with that scale can you make the pointer move sure I just have to pull down on it like this see and the harder I pull the farther the pointer moves stop pulling now get on the [Music] scale what's happening well now my whole body is pulling the scale down or is it gravity that's pulling me down that's what it is good thinking and see where the pointer is at 6 lb hey that's what I weigh well sure this is a scale but does that mean my weight tells me how hard gravity is pulling me down towards the Earth yes that's right we say that gravity is pulling you down with a force of 6 lb now let's weigh the bird okay wow that little bird doesn't even weigh one pound that means that gravity is pulling down on the bird a lot less than it is on me I mean with a lot less Force just like you said is that why a bird can go up and I can't because gravity pulls down on me more than it pulls down on the bird well no you see all that matters is whether the push up on a bird is stronger than the pull down when a bird's wings give it a strong enough push up it can fly the force of the Wings pushing a bird up is greater than the force of gravity pulling it down an airplane can go up for the same reason its wings and engine give it a push up that is greater than the force of gravity pulling it down the push up always has to be more than the pull down for something to go up into the air so that's how I make a ball go up every time I throw it up I'm giving it a push up that's stronger than the pull down gravity is giving it the ball just goes up away and then it comes back down again the harder I throw it the higher up it goes but it always slows down as it goes up then it stops and starts coming down again Earth's gravity has pulled the ball back to Earth but I wonder why don't things we send into space fall back to Earth that's because the burning Rocket Fuel keeps pushing the rocket upwards it keeps going up and up until it's in space and keeps on traveling away from the earth does the Earth's gravity still pull on things when they're in space yes but as a space vehicle keeps going farther and farther away from Earth Earth's gravity pulls PS less and less on it if a space vehicle gets close enough to something big in space like the moon then the moon's gravity will pull on it when the moon's gravity pulls harder on it than the Earth's gravity does then down becomes the direction toward the Moon is that right that's right and if you land it on the moon you'd find that its gravity doesn't pull on you as hard as Earth's gravity does so I'd weigh less there that's right and does that mean I could jump higher that's right and I wouldn't come down so fast or so hard that's right that would be nice since now I understand why I can never fall up even on the [Music] moon [Music]