A car $P$ approaching a crossing at a speed of $10\, m/s$ sounds a horn of frequency $700\, Hz$ when $40\, m$ in front of the crossing. Speed of sound in air is $340\, m/s$. Another car $Q$ is at rest on a road which is perpendicular to the road on which car $P$ is reaching the crossing (see figure). The driver of car $Q$ hears the sound of the horn of car $P$ when he is $30\, m$ in front of the crossing. The apparent frequency heard by the driver of car $Q$ is ...... $Hz$

Calculate the temperature at which the speed of sound will be two times its   ..... $K$ value at $0\,^oC$

A transverse wave is travelling along a stretched string from right to left. The figure shown represents the shape of the string at a given instant. At this instant

When a wave travels in a medium, the particle displacement is given by : $y = a\,\sin \,2\pi \left( {bt - cx} \right)$ where $a, b$ and $c$ are constants. The maximum particle velocity will be twice the wave velocity if

An organ pipe $P_1$ closed at one end vibrating in its first overtone. Another pipe $P_2$  open at both ends is vibrating in its third overtone. They are in a resonance with a  given tuning fork. The ratio of the length of $P_1$ to that of $P_2$ is

Two tuning forks $A$ and $B$ produce $8\,beats/s$ when sounded together. $A$ gas column $37.5\,cm$ long in a pipe closed at one end resonate to its fundamental mode with fork $A$ whereas a column of length $38.5\,cm$ of the same gas in a similar pipe is required for resonance with fork $B$. The frequencies of these two tuning forks, are