b
(b) \(\frac{{{\rm{Potential\, energy (}}U{\rm{)}}}}{{{\rm{Total \,energy (}}E{\rm{)}}}} = \frac{{\frac{1}{2}m{\omega ^2}{y^2}}}{{\frac{1}{2}m{\omega ^2}{a^2}}} = \frac{{{y^2}}}{{{a^2}}}\)
So \(\frac{{2.5}}{E} = \frac{{{{\left( {\frac{a}{2}} \right)}^2}}}{{{a^2}}}\)
==> \(E = 10J\)