1. The difference in sound between 33 and 45 has nothing to do with the amount of energy being put into the stylus or the energy in the system. It has to do with less information density on the groove. There is greater length groove per second of musical signal. Lower information density, which is storing the same information in a greater storage area/length/volume (depending on the technology) gives greater fidelity. This is true in records, tape (30ips instead of 15ips, for instance), photography (a 4" x 5" negative compared to 35mm, which is 1" x 1.5", movie film....any analog medium.
This is a huge thing, and it is why more tape run by the head, more groove length under the stylus, and greater info on a negative enlarged to the same size all yield great improvements. The record does not play louder with a 45, which it would with higher modulation, the tape does not play louder.
2. As for energy, you are mixing energies. Energy put into moving the cantiliver is the same or volume would be louder. Kinetic energy of the platter is higher, yes, but that has nothing to do with playback and has nothing to do with more energy put into the cartridge, which is not done.
But, there is more kinetic energy in the platter. You are wondering about it. Well, where it came from is the energy put into it by the motor. That kinetic energy came from the torque required to get it up to speed over the period of time of acceleration. That energy is = i(w x w) where w (omega) = rotational velocity and i is the moment of the inertia of the platter. That energy stays constant, and when the switch is turned off the energy gets bled off, turning into heat, in the bearings and motor "off torque". That amount of energy during deceleration = the amount of acceleration = the kinetic energy while the platter was turning. Thus, energy is neither created nor destroyed, but is conserved, only changing forms. Newton is satisfied. Or at least his laws are, I trust he is dis-satisfied about how much physics is twisted and mutilated in this industry!
And finally, here is the bit of wrong information on the forum John sent us to, written by a "John" on that forum.
There is no centripetal force involved, as the arm is not rotating with the record. Now, if we put the whole turntable and tonearm mechanism on a rotating sub table and rotated the subtable then the cartridge would indeed try to fly outward.
But I know of nobody spinning their ENTIRE turntable setup while playing a record, so there is not such force.
It is a great optical illusion: stylus on a rotating record, so it must fly outward! False illusion. Spin the platter faster and faster and faster and there still is no centripetal force: only the platter is spinning! There can be no such force as the velocity of the stylus/cartridge/headshell in the tangential direction is essentially zero.
Don't worry about getting this wrong, most first year physics students would. A lifetime studying and working in physics and engineering: there's no substitute for that plus the education beforehand. Nobody should feel bad about that, I do not feel bad about not knowing as much about their respective fields as my doctor and lawyer do!
