A speeding motorcyclist sees traffic jam ahead him. He slows down to 36 km hour^$$-$$1. He finds that traffic has eased and a car moving ahead of him at 18 km hour^$$-$$1 is honking at a frequency of 1392 Hz. If the speed of sound is 343 m s^$$-$$1, the frequency of the honk as heard by him will be

The number of possible natural oscillations of air column in a pipe closed at one end length 85 cm whose frequencies lie below 1250 Hz are (Velocity of sound = 340 m s^$$-$$1)

The length of the wire between two ends of a sonometer is 100 cm. What should be the positions of two bridges below the wire so that the three segments of the wire have their fundamental frequencies in the ratio 1 : 3 : 5.

Two sources P and Q produce notes of frequency 660 Hz. each. A listener moves from P to Q with a speed of 1 ms^$$-$$1. If the speed of sound is 330 m/s, then the number of beats heard by the listener per second will be