Question

A wave has a wavelength of 7 mm and a frequency of 19 hertz. What is its speed?

Answer 1

Speed = (frequency) x (wavelength)

Speed = (19 per second) x (7 mm)

Speed = (19 x 7) (per second · mm)

Speed = 133 mm/sec

or you might want to write Speed = 0.133 m/s .