(b) $\frac{Potential\ energy\ (U)}{Total\ energy\ (E)} = \frac{\frac{1}{2}m\omega^{2}y^{2}}{\frac{1}{2}m\omega^{2}a^{2}} = \frac{y^{2}}{a^{2}}$ $So\ \frac{2.5}{E} = \frac{\left( \frac{a}{2} \right)^{2}}{a^{2}} \Rightarrow E = 10J$
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.