Find the time period of mass $M$ when displaced from its equilibrium position and then released for the system shown in the figure.

Vedclass pdf generator app on play store
Vedclass iOS app on app store
(N/A) Let the spring constant be $k$. When the mass $M$ is displaced downwards by a distance $x$,the pulley moves down by $x$. Since the string is inextensible and passes over the pulley,both sides of the string attached to the pulley must move down by $x$. This causes the spring to stretch by an additional $2x$.
The change in the spring force is $\Delta F = k(2x) = 2kx$.
Since the string is connected to the pulley on both sides,the restoring force $F_{rest}$ acting on the mass $M$ is the sum of the tension changes on both sides of the pulley. Each side of the string experiences a tension change of $\Delta T = k(2x) = 2kx$.
Therefore,the total restoring force is $F_{rest} = 2 \times \Delta T = 2 \times (2kx) = 4kx$.
Comparing this with the standard $SHM$ restoring force equation $F = -k_{eff}x$,we get the effective spring constant $k_{eff} = 4k$.
The time period $T$ of the system is given by $T = 2\pi \sqrt{\frac{M}{k_{eff}}} = 2\pi \sqrt{\frac{M}{4k}} = \pi \sqrt{\frac{M}{k}}$.

Explore More

Similar Questions

Two bodies $M$ and $N$ of equal masses are suspended from two separate massless springs of force constants $k_1$ and $k_2$ respectively. If the two bodies oscillate vertically such that their maximum velocities are equal,the ratio of the amplitude of $M$ to that of $N$ is

When a particle of mass $m$ is attached to a vertical spring of spring constant $k$ and released,its motion is described by $y(t) = y_{0} \sin^{2} \omega t$,where $y$ is measured from the lower end of the unstretched spring. Then $\omega$ is

The potential energy of a particle of mass $m$ situated in a unidimensional potential field varies as $U(x) = U_0(1 - \cos ax)$,where $U_0$ and $a$ are constants. The time period of small oscillations of the particle about the mean position is

Difficult
View Solution

$A$ mass $m$ is vertically suspended from a spring of negligible mass; the system oscillates with a frequency $n$. What will be the frequency of the system if a mass $4m$ is suspended from the same spring?

$A$ vertical spring oscillates with a period of $6 \ s$ when a mass $m$ is suspended from it. When the mass is at rest,the spring is stretched through a distance of (Take acceleration due to gravity $g = \pi^2 = 10 \ m/s^2$): (in $m$)

Vedclass Products

For Students

Vedclass Test Series

Mock tests in real JEE/NEET style with performance analysis. 5-day free trial.

Start Free Trial
For Teachers

Exam Paper Generator

Generate Set A/B/C/D exam papers from 7.5L+ questions in 2 minutes. 3 chapters free.

Try Free
For Institutes

Online Exam Module

Live online exams with unlimited students, 360° analytics & white-label branding.

See Demo