Harmonic oscillator and simple pendulum time period

[anorlunda]

Harvesting energy? Is that what is taught in field theory courses?

See https://en.wikipedia.org/wiki/Energy_harvesting

 

[Ahzmandius]

The force applied to the mass is the same no matter how long it is (at least for small angles), so the tangential velocity is the same too. The angular velocity is not the same because of:

w = v/L

The angular velocity for a longer L is less, and for a shorter L more. You need more time to pass the same angle with longer L because arc length is longer.