I've been doing physics problems from Barron's chapter 4, and usually I get them correct. The trouble is, I don't know why I get them correct. All I'm doing is plugging the numbers into the formulas which I have attempted to memorize. It's the opposite of those frustrating mathematical moments I described about a year ago (for instance, when I was studying Logarithms) where I could not get any of the problems right even though I understood what was required to solve them.

This part of classical mechanics seems to be a shifting kaleidoscope of different quantities such as impulse, momentum, angular momentum, spatial extension, velocity, acceleration, mass, weight, gravity, time and force, all of which seem to be able to be multiplied by each other despite their very different qualities. Kilograms/meters/seconds, velocity²/radius length, and force * time. I am finding it hard to keep track of all of them. The problems are solved by combining and recombining them in the formulas. I am remotely aware that all of these things profoundly and precisely describe the "rea,l" at least the macroscopic, world, but I feel far away from experiencing them and understanding how they really do combine. Newton's apple has not dropped from the tree, it is still floating up there as if gravity had no pull on it, as if there were no Newtons of force acting upon it. But what's the difference between the force of gravity and the acceleration of gravity? Will I ever eat the apple?

What's the point of getting the problems right if I don't understand the material? And then should I dare to ask questions? If momentum is mass x velocity, then do photons, which have no mass but do have velocity, have momentum? Yeah, I shouldn't ask about photons, it seems like it will be years before I advance enough in physics to deal with them rather than with cannonballs, wheels, and orbiting Keplerian planets.

I know that these formulaic entities are part of my real life; my Electron Car's path along the road is a complex combination of forces and vectors and acceleration and friction and torque and momentum. I have no laboratory or workshop where things can be isolated and demonstrated, though I suppose I could find space somewhere if I tried. But the world is so full of phenomena that I hardly know where to start.

Posted at 1:08 am | link