Aharmonic oscillator has angular frequency v and amplitude a. (a) what are the magnitudes of the displacement and velocity when the elastic potential energy is equal to the kinetic energy? (assume that u = 0 at equilibrium.) (b) how often does this occur in each cycle? what is the time between occurrences? (c) at an instant when the displacement is equal to a> 2, what frac- tion of the total energy of the system is kinetic and what fraction is potential?