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[Phys-L] Re: A Third law question



I think John has it right here.

The question "where did the force come from" is unanswerable.

I think this is a wonderful time to say "I don't know" and guess what...
neither does anybody else. We need to make clear to our students that there
are many mysteries out there that no one has found the answers to.

1.What is it about a massive object that causes it to have inertia?
Answer... I don't know it is something that we have noticed stuff has.

2. What is it about two massive objects that cause them to have a
gravitational attraction toward each other? Answer... I don't know, it is
something that we have noticed that massive bodies have.

3.What is it about objects that cause them to have charge and therefore
attract and repel each other? Answer I don't know, it is something that we
have noticed that stuff has.

To your student who brilliantly asks 'Where does the disk get the extra
force when I push up with more force than its weight?' your first response
should be, what a wonderful question! The answer is from its resistance to
change in motion. Where does the disk get its ability to resist change in
motion. See #1 above.