A source produces 15 crests and 15 throughs in 3 seconds. When the second crest in produced, the first is `2 cm` away from the source. Calculate (a) frequency (b) wavelength ( c) speed of the wave.

In a certain gas, a source produces 40,000 compression and 40,000 rarefaction pulses in 1 sec. When the second compression pulse is produced, the first is 1cm away from the source. Calculate the wave speed.

In a certain gas, a source produces 40,000 compression and 40,000 rarefaction pulses in 1 sec. When the second compression pulse is produced, the first is 1cm away from the source. Calculate the wave speed.