Question
A 2 in long string fixed at both ends is set into vibrations in its first overtone. The wave speed on the string is 200m/s and thee amplitude is 0.5cm.
  1. Find the wavelength and the frequency.
  2. Write the equation giving the displacement of different points as a function of time. Choose the X-axis along the string with the origin at one end and t = 0 at the instant when the point x = 50cm has reached its maximum displacement.

Answer


$\text{V}=200\text{m/s},\ 2\text{A}=0.5\text{m}$

  1. The string is vibrating in its 1st overtone

$\Rightarrow\lambda=1=2\text{m}$

$\Rightarrow\text{f}=\frac{\text{v}}{\lambda}=100\text{Hz}$

  1. The stationary wave equation is given by

$\text{y}=2\text{A}\cos\frac{2\pi\text{x}}{\lambda}\sin\frac{2\pi\text{Vt}}{\lambda}$

$=(0.5\text{cm})\cos\big[(\pi\text{m}^{-1})\text{x}\big]\sin\big[(200\pi\text{s}^{-1})\text{t}\big]$

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

Show that when a particle is moving in S.H.M. its velocity at a distance $\frac{\sqrt{3}}{2}$ of its amplitude from the central position is half its velocity in central position.
Find an expression for the orbital velocity of a satellite revolving around the earth in a circular orbit at a height h above the surface of earth.
The resultant of two vector $\vec{P}$ and $\vec{Q}$ is $\vec{R}$. If the direction of $\vec{Q}$ is reversed, then the resulting vector becomes $\vec{S}$. Then prove that,
$
R ^2+ S ^2=2\left( P ^2+ Q ^2\right)
$
Figure shows a smooth pair of thick metallic rails connected across a battery of emf $\in$ having a negligible internal resistance. A wire ab of length l and resistance r can slide smoothly on the rails. The entire system lies in a horizontal plane and is immersed in a uniform vertical magnetic field B. At an instant t, the wire is given a small velocity u towards right.
  1. Find the current in it at this instant. What is the direction of the current?
  2. What is the force acting on the wire at this instant?
  3. Show that after some time the wire ab will slide with a constant velocity. Find this velocity.

What is the angular velocity at any point on the equator so that the body feels weightlessness?
A 20 cm thick layer of ice has been formed on the surface of a freshwater lake during extreme winter. The temperature of the air is $-10^{\circ} C$. Find how long will it take for another 1 mm layer of water to freeze? Thermal conductivity of ice $=2.1 W m ^{-1} K^{-1}$, latent heat of fusion of water $=3.36 \times 10^5 J kg ^{-1}$ and density of ice $=10^3$ $kg m ^{-3}$.
Prove that the vectors $\vec{\text{A}}=2\hat{\text{i}}-3\hat{\text{j}}+\hat{\text{k}}$ and $\vec{\text{B}}=\hat{\text{i}}+\hat{\text{j}}+\hat{\text{k}}$ are mutuallly perpendicular.
  1. Explain the term impulse. Show that impulse of a variable force is equal to the area enclosed by the force-time curve.
  2. Two masses 8kg and 12kg are connected at the two ends of a light inextensible string that passes over a frictionless pulley. Find the acceleration of the masses and tension in the string, when the masses are released.

If the frequency of a tuning fork is 256Hz and speed of sound in air is 320m/s, find how far does the sound travel when the fork executes 64 vibrations?