A source of sound S emitting waves of frequency 100 Hz and an observer O are located at some distance from each other. The source is moving with a speed of 19.4 m s^$$-$$1 at an angle of 60^o with the source observer line as shown in the figure. The observer is at rest. The apparent frequency observed by the observer (velocity of sound in air 330 m s^$$-$$1), is

4.0 g of a gas occupies 22.4 litres at NTP. The specific heat capacity of the gas at constant volume is 5.0 J K^$$-$$1 mol^$$-$$1. If the speed of sound in this gas at NTP is 952 m s^$$-$$1, then the heat capacity at constant pressure is
(Take gas constant R $$=$$ 8.3 J K^$$-$$1 mol^$$-$$1)

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)

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