re: #89 LudwigVanQuixote

OK. If the forces are canceled, and they are always canceled when you are standing on the floor. How do you ever jump up?

500 Quixote points to a non physicist lizard who gets this.

Because you push the earth down an equivalent amount. It’s just that Earth with its huge mass goes “down” only a teeny tiny bit; you with your small mass go way “up” a lot.

Then when you “fall” the earth is sucking you back down; but your mass is also sucking the earth back up that same teenty tiny bit.

it’s easier to understand when you get rid of the concepts of up and down. I find it easier to turn the “diagram’ sideways so that the two bodies are simply moving “away” from each other, with no point of reference being preferred.