Q121 / 180 · AIIMS 2004 · Physics
Two springs are connected to a block of mass $M$ placed on a frictionless surface as shown in the figure. If both the springs have a spring constant $k$, the frequency of oscillation of the block is


- A$\frac{1}{2 \pi} \sqrt{\frac{k}{M}}$
- Correct answerB$\frac{1}{2 \pi} \sqrt{\frac{k}{2 M}}$
- C$\frac{1}{2 \pi} \sqrt{\frac{2 k}{M}}$
- D$\frac{1}{2 \pi} \sqrt{\frac{M}{k}}$.
Solution
The spring constant of spring connected in series is equal to
$$
k_s=\frac{k_1 k_2}{k_1+k_2}=\frac{k}{2}\left(F_{\text {or }} k=k_2=k\right)
$$
Thus frequency of oscillation of given system is
$$
f=\frac{1}{2 \pi} \sqrt{\frac{k}{2 m}}
$$
Hence, the correct answer is option: 'B'.