The Frog's Window. 2025/11/12.
(East Japanese Tree Frog)

So if I'm referencing the the directions anyway when justifying the unit choice, maybe meter-newtons would be better. :)

In one sense... the units "belong to" the magnitude, so they have no directionality and there's no need to preserve the order of the cross product.

OTOH, I tell my students not to write torques in joules because a joule comes from parallel F and x vectors, and torques from perpendicular ones...

Thank you for this--I knew there was some terminology from curves but I couldn't remember it clearly enough to search up the names.

This ambiguity is part of what I was fishing for weeks back when I asked it people think of radial and centripetal as being slightly different! I thought maybe people viewed, say, "1" as centripetal but "2" as radial or vice versa. But nobody said anything of the sort.

I want all four of these to have distinct names and I'm not sure I've ever seen that done before. Is there a convention for this I'm not aware of? Does anybody have a way they personally do it that they like? #ITeachPhysics #AstroEdu

1: Toward the central body
2: Perpendicular to that
3: Toward the local center of curvature
4: Perpendicular to that

I feel like people call both 1 and 3 centripetal/radial, but obviously they're different. One can cause speed changes and the other can't! #ITeachPhysics #AstroEdu

I introduced the universal gravitational constant yesterday, and to my knowledge NONE of my kids noticed or joked about the value! I'm going to need to point it out I think.

4. Other good charts, like this look at where and when certain behaviors are acceptable.

Good hypothesis! Seems pretty plausible.

In the third value, I calculated the the speed (and then force) using the graph's period instead of the metronome's period.

In the handful of tests I did, the metronome period seemed to lead to force values that matched my measured force better than the graph period.

Ahhh, I see... So you're recommending an measuring an accelerometer measurement instead of a force sensor. I suppose if I protect my smart carts we could just swing them around instead...