The driver of a car travelling with speed 30 m/s towards a hill sounds a horn of frequency 600 Hz. If the velocity of sound in air is 330 m/s, the frequency of reflected sound as heard by driver is

Each of the two strings of length 51.6 cm and 49.1 cm are tensioned separately by 20 N force. Mass per unit length of both the strings is same and equal to 1 g/m. When both the strings vibrate simultaneously the number of beats is

The wave described by y = 0.25 sin(10$$\pi $$x $$-$$ 2$$\pi $$t), where x and y are in metres and t in seconds, is a wave travelling along the

Two periodic waves of intensities $$I$$₁ and $$I$$₂ pass through a region at the same time in the same direction. The sum of the maximum and minimum intensities is