Open-open pipes support both even and odd harmonics, so an open pipe is richer in harmonics than a closed-one which supports only odd harmonics.
825
Velocity of sound in a gaseous medium is 330 m/s. If the pressure is increased by 4 times without change in temperature, the velocity of sound in the gas is:
For a source moving toward a stationary observer, observed frequency increases: f_o = f * v/(v - v_source).
827
A sound source of frequency 170 Hz is placed near a wall. A man walking from the source towards the wall finds that there is a periodic rise and fall of sound intensity. If speed of sound in air is 340 m/s, then distance separating the two adjacent positions of minimum intensity is:
Adjacent minima occur when path difference changes by λ/2; λ = v/f = 340/170 = 2 m, so λ/2 = 1 m.
828
Two identical tuning forks vibrate at 256 c/sec. After loading one of them, 6 beats/sec are heard when forks are sounded together. The period of the loaded fork is:
For diatomic gases like air, the ratio of specific heats γ is approximately 1.4.
830
A stretched wire with clamped ends has a fundamental frequency of 1,000 Hz. What will be the new fundamental frequency if tension in the wire is increased by 2%?
