A body of mass \(1.5 kg\) is fastened to a spring, and lies on a horizontal frictionless table. When the mass is pulled with a force of \(32 N\), the extension in the spring is \(0.35 m\). Calculate the maximum kinetic energy for a simple harmonic oscillation when the initial displacement is \(0.2 m\).
A. 9.80J B. 9.44J C. \(1.83 J\) D. \(0.45 J\)
Correct Answer: C
Explanation
given: \(m=1.5 kg\), \(f=32 N , e=0.35\) \(\max K . E = m\) we can also show that \(K \cdot E_{\max }=\frac{1}{2} K A^{2}\). Where \(k\) is a constant of proportionality known as elastic constant from \(\omega=\sqrt{\frac{k}{m}}\) and \(1-\omega . A\) thus, \(v=\sqrt{\frac{h}{m}} A\) and \(K \cdot E=\frac{1}{2} m \cdot \sqrt{\frac{h}{m} \cdot 4}\) \(=\frac{1}{2} \cdot m_{1} \cdot \frac{k}{m_{1}}+=\frac{1}{2} h .4\)lso \(F=h\) \begin{aligned} &k=\frac{f}{e}=\frac{32}{0.35}=91.428 N / m\\ &\text { for } \max K . E, A=0.2 m\\ &\therefore K . E=1 / 2 \times 91.42857 \times 0.2^{2}\\ &=1.83 J\\ &\text { Alternatively, }\\ &K \cdot E_{\max }=\frac{1}{2} m v_{\max }^{2}\\ &=\frac{1}{2} k A^{2}\\ &\text { where } K=\frac{F}{e}=\frac{32}{0.35}\\ &\text { for maximum } K . E . \text {, }\\ &A=0.2 m\\ &\text { K.E. }=\frac{1}{2} \times \frac{32}{0.35} \times 0.22\\ &=1.83 J \end{aligned}