MCQ
A pan with set of weights is attached with a light spring. When disturbed, the mass-spring system oscillates with a time period of $0.6$ $s.$ When some additional weights are added then time period is $0.7s.$ The extension caused by the additional weights is approximately given by ......... $cm$
  • A
    $1.38$
  • $3.5 $
  • C
    $1.75$
  • D
    $2.45$

Answer

Correct option: B.
$3.5 $
b
(b) $2\pi \sqrt {\frac{m}{k}} = 0.6$ …$(i)$ and $2\pi \sqrt {\frac{{m + m'}}{k}} = 0.7$ …$(ii)$

Dividing $(ii)$ by $(i)$ we get ${\left( {\frac{7}{6}} \right)^2} = \frac{{m + m'}}{m} = \frac{{49}}{{36}}$

$\frac{{m + m'}}{m} - 1 = \frac{{49}}{{36}} - 1 \Rightarrow \frac{{m'}}{m} = \frac{{13}}{{36}}$ $⇒$ $m' = \frac{{13m}}{{36}}$

Also $\frac{k}{m} = \frac{{4{\pi ^2}}}{{{{(0.6)}^2}}}$

Desired extension $ = \frac{{m'g}}{k}$$ = \frac{{13}}{{36}} \times \frac{{mg}}{k}$

$ = \frac{{13}}{{36}} \times 10 \times \frac{{0.36}}{{4{\pi ^2}}} \approx 3.5\;cm$

Need a full question paper?

Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.

Start Generating Free

Similar questions

A resistance of $40 \,\Omega$ is connected to a source of alternating current rated $220\, V , 50 Hz$. Find the time taken by the current to change from its maximum value to $ms$ value
Match List-$I$ with List-$II$ :

List-$I$ List-$II$
$(A)$  A force thatrestores anelastic body of unit area to its original state $(I)$ Bulkmodulus
$(B)$  Two equal andopposite forcesparallel toopposite faces $(II)$Young'smodulus
$(C)$Forcesperpendiculareverywhere tothe surface perunit areasameeverywhere $(III)$ Stress
$(D)$Two equal andopposite forceperpendicular toopposite faces $(IV)$ Shearmodulus

Choose the correct answer from the options given below:

The transverse displacement of a string (clamped at its both ends) is given by

$y(x,t)\, = \,0.6\,\sin \,\left( {\frac{{2\pi }}{3}x} \right)\,\cos \,(120\,\pi t)$

where $x$ and $y$ are in $metre$ and $t$ in $second$ . The length of the string is $1.5\,m$ and its mass is $3.0\times 10^{-2}\,kg$ the tension in the string will be .... $N$

A whistle emitting a loud sound of frequency $540 \,Hz$ is whirled in a horizontal circle of radius $2 \,m$ and at a constant angular speed of $15 \,rad / s$. The speed of sound is $330 \,m / s$. The ratio of the highest to the lowest frequency heard by a listener standing at rest at a large distance from the centre of the circle is
The maximum speed that can be achieved without skidding by a car on a circular unbanked road of radius $R$ and coefficient of static friction $\mu $, is
A boat crosses a river with a velocity of $8\, km/h$. If the resulting velocity of boat is $10 \,km/h $ then the velocity of river water is...........$km/h$
In an electromagnetic wave the energy density associated with magnetic field will be
$A$ ball is thrown vertically downwards with velocity $\sqrt {2gh} $ from $a$ height $h$. After colliding with the ground it just reaches the starting point. Coefficient of restitution is
A sample of radioactive element containing $4 \times 10^{16}$ active nuclei. Half life of element is $10$ days, then number of decayed nuclei after $30$ days is  ........ $\times 10^{16}$ 
$20\,\mu A$ current flows for $30$ seconds in a wire, transfer of charge will be