Answer: 5 Hz
Formula: Frequency = Velocity/Wavelength
Workings
To calculate the velocity
Velocity = distance/time
= 45cm / 3sec
Velocity = 15 cm/sec
To calculate wavelength
Wavelength is defined as the distance traveled by a wave from one crest to another.
Since we are told that 15 pulses travel a distance of total 45 cm,
⇒ Distance traveled by 1 pulse will be = 45 cm/15
Wavelength = 3 cm
To calculate Frequency
Frequency = Velocity/Wavelength
Velocity = 15 cm/sec
Wavelength = 3 cm
Frequency = 15/3 Hz
Frequency = 5 Hz
