Quantum Simple Harmonic Oscillator

[jkg]

Homework Statement

The period of a macroscopic pendulum made with a mass of 10 g suspended from
a massless cord 50 cm long is 1.42 s. (a) Compute the ground state (zero-point) energy. (b) If the
pendulum is set into motion so that the mass raises 0.1 mm above its equilibrium position, what will
be the quantum number of this state? (c) What is the frequency of motion in (b)?

Need help! I keep doing the problem but getting the wrong answers. I got A but am not getting B. the answer to B is 2.1*10^28

 

[ideasrule]

What are the energies of the excited states? By how much does the harmonic oscillator's energy increase when the pendulum is raised 0.1 mm? Which excited-state energy does this correspond to?