MCQ
A wire of length one metre under a certain initial tension emits a sound of fundamental frequency $256 \,Hz$. When the tension is increased by $1 \,kg$ wt, the frequency of the fundamental node increases to $320 \,Hz$. The initial tension is ........... $kg \,wt$
  • A
    $3 / 4$
  • B
    $4 / 3$
  • $16 / 9$
  • D
    $20 / 9$

Answer

Correct option: C.
$16 / 9$
c
(c)

Let tension be $T$

$f_1=\sqrt{\frac{T}{\mu}} \times \frac{1}{2 l}=256$

$f_2=\sqrt{\frac{T+10}{\mu}} \times \frac{1}{2 l}=320$

$\sqrt{\frac{T}{T+10}}=\frac{256}{320}$

$\frac{T}{T+10}=\frac{(16)^2}{(16)^2 \times(20)^2}$

or $\frac{T}{T+10}=\frac{16^2}{(20)^2}$

or $400 T=256 T^2+2560$

or $144 T=2560$

or $T=\frac{2560}{144}$

or $T=\frac{2560}{16 \times 9}$

or $T=\frac{160}{9}$ Newton

$=\frac{16}{9} \,kg -w t$

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

The angle between $(\overrightarrow A - \overrightarrow B )$ and $(\overrightarrow A \times \overrightarrow B )$ is $(\overrightarrow{ A } \neq \overrightarrow{ B })$
The two thigh bones (femurs), each of cross-sectional area $10\; cm ^{2}$ support the upper part of a human body of mass $40\; kg$. Estimate the average pressure sustained by the femurs.
When a ball is thrown vertically upward with velocity $u$, it rises to a height $h$. If it is thrown with velocity $2 u$ then the height obtained will be :
How many wavelength of $Kr^{86}$ are there in $1m?$
A wheel is of diameter $1\ m.$ If it makes $30$ revolution per second, then the linear speed of a point on its circumference will be 
As compared to ${ }^{12} \mathrm{C}$ atom, ${ }^{14} \mathrm{C}$ atom has:
A rigid body can be hinged about any point on the $x$ -axis. When it is hinged such that the hinge is at $x$, the moment of inertia is given by $I = 2x^2 - 12x + 27$ The $x$ -coordinate of centre of mass is
A particle is projected from ground at an angle $\theta$ with horizontal with speed $u$. The ratio of radius of curvature of its trajectory at point of projection to radius of curvature at maximum height is ........
Match List $I$ with List $II$ :

List $I$ List $II$
$A$ Isothermal Process $I$ Work done by the gas decreases internal energy
$B$ Adiabatic Process $II$ No change in internal energy
$C$ Isochoric Process $III$ The heat absorbed goes partly to increase internal energy and partly to do work
$D$ Isobaric Process $IV$ No work is done on or by the gas

Choose the correct answer from the options given below :

The length of the two rods made up of the same metal and having the same area of cross-section are $0.6 m$ and $0.8 m$ respectively. The temperature between the ends of first rod is ${90^o}C$ and ${60^o}C$ and that for the other rod is $150^oC$ and ${110^o}C$. For which rod the rate of conduction will be greater