Question

A force of 6.4 N stretches a vertical spring by 0.1 m. The mass that must be suspended from the spring so that it oscillates with a period of ($\pi /4$) sec is:

• A. $\left(\pi /4\right)$ kg
• B. 1 kg
• C. $\left(1/\pi \right)$
• D. 10 kg

Answer 1

The correct option is B 1 kg

$\begin{array}{c}k=\frac{f}{x}=\frac{6.4}{0.1}=64\\ T=2\pi \sqrt{\frac{m}{k}}\\ \frac{\pi }{4}=2\pi \sqrt{\frac{m}{64}}\\ m=1kg\end{array}$

Hence,

option $\left(B\right)$ is correct answer.