Applied Mathematician, Julia programmer, father of two amazing boys, official coonhound mix mutt-walker.
PhD in Civil Engineering. Debian Linux user since ca […]
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Daniel Lakeland
To make that balance work, probably we'll want to groove out a little bit of wood to let the marbles rest securely. That should be doable with a v chisel, I think we have one.
I remember reading in Feynman's Lectures on #physics that conservation of angular momentum implied conservation of linear momentum in the limit when you take rotation about a point infinitely far away. But that conservation of linear momentum doesn't imply conservation of angular momentum. In […]
Today in #physics from scratch we are going to do the following calculation. Having dropped the ball and noticed it doesn't turn, and noticed that it gets faster and faster from zero speed, we assume it grows linearly and get an expression for it. Using this expression we can show that an […]
@johncarlosbaez
While it was hovering in front of me unmoving, Spun it up to high spin rates by doing some work... and then slowed myself down to my original frame of reference... The work I did on spinning the ball would be added to the kinetic energy I would measure for the ball from my […]
Also, all the practical conservation laws are included: mass, linear momentum, angular momentum, and energy.
After we are done with rolling balls, I think one of the key experiments will be balancing things. Clamp a razor blade in a bench vise... and get a piece of hardwood from a hobby store […]
I really think rolling balls is a super way to start teaching physics. First off, the experimental setup is cheap and easy, and doesn't require exotics like an air-hockey table or a 1D air-track. Second of all you have to explain the difference between rolling and sliding/falling because it's […]
Alex's idea of rolling a magnet down a magnet board was a pretty good idea, so when he had his friend over, we ran the experiment. We did it at a high angle, and directly vertical. We also dropped the magnet in free space... Dropping was from a low height […]
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@johncarlosbaez
I should be able to formulate this as an integral over the volume of a velocity field formed by a rotation around CM and a constant v0 superimposed though. I just haven't looked at the algebra yet.
Ok #physics friends. My brain wants to say that a rolling ball has two forms of kinetic energy. one the kinetic energy it would have from pure translation, and one the kinetic energy it would have from pure rotation (say floating in mid air rotating). That these can be calculated independently […]
