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If your model can't be used to predict things in reality, then what good is it? If I throw a feather down from a rooftop and then I let a brick fall down, the brick will hit the earth first. The heavier thing falls "faster".

You can use a bunch of words to explain what's really going on there, but it won't change that the brick hits the earth first, hence it falls faster. Unless you can predict the future correctly and communicate this simply to your peers, what's the point of being correct in the terminology?



I distinguished between velocity and acceleration.

My point was strictly that many people will falsely think gravity somehow meaningfully pulls lighter objects at a lower rate. This despite days off lessons that gravity on Earth is basically a constant.

That is to say, if your model of speed of things falling is hinged solely on gravity, it will not be predictive in the extremes.

Of course, most folks aren't playing in the extremes, so the simple model will be fairly predictive of everything they do actually toss around the room. Can easily explain why the stack of books fell at the same speed as the basketball when the dresser was knocked over. :)


Doesn't explain why the paper plane glides, though. I was always frustrated in physics class. There just wasn't enough precision to describe reality and everytime a test said "ignore friction" I would mentally shout out "but there is friggin' friction". Math made a lot more sense and it was only with advanced math knowledge that I would finally be able to make sense of some of the entry physics stuff.

If only they had told me everything (including friction), then maybe phyics would have made a lot more sense to me. But then again, school math never even mentioned imaginary numbers. School is very incomplete.


And yet friction alone wouldn't do it, either. Consider balloons.

Same goes for everything underwater. Which follows from viewing air as a medium you are traveling through.

Are there bad teachers that need to more honestly cover some of the assumptions? Yes. They are a useful tool, though.


Because science aims to discover what is really going on under the hood. And that matters. By breaking the problem into vacuum and non vacuum you get a better understanding.




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