Systems in simple harmonic motion, or harmonic oscillators, obey the law of conservation of energy just like all other systems do. Using energy considerations, one can analyze many aspects of motion of the oscillator. Such an analysis can be simplified if one assumes that mechanical energy is not dissipated. In other words,
E = K + U = Constant
where E is the total mechanical energy of the system, K is the kinetic energy, and U is the potential energy.
a). Find the kinetic energy K of the block at the moment labeled B.
Express your answer in terms of k and A.
It finds the kinetie energy of a harmonic oscillator.