A string of mass $m$ and length $l$ hangs from ceiling as shown in the figure. Wave in string moves upward. $v_A$ and $v_B$ are the speeds of wave at $A$ and $B$ respectively. Then $v_B$ is
$\sqrt 3v_A$
$v_A$
$< v_A$
$\sqrt 2v_A$
A wave travelling along the $x- $ axis is described by the equation $y(x, t) = 0.005\,\,cos(\alpha x\,-\,\beta t).$ If the wavelength and the time period of the wave are $0.08 \,\,m$ and $2.0\,\,s,$ respectively, then $\alpha $ and $\beta $ in appropriate units are
A transverse wave is passing through a stretched string with a speed of $20\ m/s$ . The tension in the string is $20\ N$ . At a certain point $P$ on the string, it is observed that energy is being transferred at a rate of $40\ mW$ at a given instant. Find the speed of point $P$
The velocities of sound at the same pressure in two monatomic gases of densities ${\rho _1}$ and ${\rho _2}$ are $v_1$ and $v_2$ respectively. ${\rho _1}/{\rho _2} = 2$, then the value of $\frac{{{v_1}}}{{{v_2}}}$ is
A sound absorber attenuates the sound level by $20\, dB$. The intensity decreases by a factor of
Equation of a plane progressive wave is given by $y = 0.6\, \sin 2\pi \left( {t - \frac{x}{2}} \right)$.On reflection from a denser medium its amplitude becomes $2/3$ of the amplitude of the incident wave. The equation of the reflected wave is :-