The mechanical energy of a damped oscillator becomes half of its initial energy in $4 \ s$. In another $t \ s$,its mechanical energy becomes $12.5 \%$ of its initial mechanical energy. Then $t=$ (in $s$)

Four pendulums $A, B, C$ and $D$ are hung from the same elastic support as shown in the figure. $A$ and $C$ are of the same length,while $B$ is shorter than $A$ and $C$,and $D$ is longer than $A$. If $A$ is given a displacement,then at steady state:

When two violin wires with different fundamental frequencies are vibrated to play some music,can they produce resonance?

$A$ block of mass $200 \, g$ is executing $SHM$ under the influence of a spring with spring constant $K = 90 \, N \, m^{-1}$ and a damping constant $b = 40 \, g \, s^{-1}$. The time elapsed for its amplitude to drop to half of its initial value is ...... $s$ (Given $\ln \frac{1}{2} = -0.693$).

$A$ body of mass $0.3 \ kg$ hangs by a spring with a force constant of $50 \ N/m$. The amplitude of oscillations is damped and reaches $1/e$ of its original value in about $100$ oscillations. If $\omega$ and $\omega^{\prime}$ are the angular frequencies of undamped and damped oscillations respectively, then the percentage value of $\left(\frac{\omega-\omega^{\prime}}{\omega}\right) \times 100$ is:

The amplitude of a damped oscillator becomes $\left(\frac{1}{3}\right)$ of its original amplitude in $2 \ s$. If its amplitude after $6 \ s$ becomes $\left(\frac{1}{n}\right)$ times the original amplitude,the value of $n$ is ($n$ is a non-zero integer).