Two speakers $A$ and $B$, placed $1 \mathrm{m}$ apart, each produce sound waves of frequency $1800 \mathrm{Hz}$ in phase. A detector moving parallel to line of speakers distant $2.4 \mathrm{m}$ away detects a maximum intensity at $O$ and then at $P.$ Speed of sound wave is

Assertion : Television signals are received through skywave propagation.

Reason : The ionosphere dose not electromagnetic waves of frequencies greater than a certain critical frequency

The displacement of a wave disturbance propagating in the positive x-direction is given by $y=1/(1+x^2)$ at time $t=0$ and $y=1/[1+(x–1{)}^2]$ at $t=2 \mathrm{s}$ where $x$ and $y$ are in $\mathrm{meters}$. The shape of the wave disturbance does not change during the propagation. The velocity of the wave is:

Two blocks each having a mass of $3.2 \mathrm{kg}$ are connected by a wire $CD$ and the system is suspended from the ceiling by another wire $AB$ (figure). The linear mass density of the wire $AB$ is $10 \mathrm{g}/\mathrm{m}$ and that of $CD$ is $8 \mathrm{g}/\mathrm{m}.$ The speed of a transverse wave pulse produced in $AB$ and in $CD$ are :