Waves ( Physics)

Diagram 1 shows a wave moving through a slinky roll.
Diagram 1 menunjukkan satu gelombang  merambat melalui gegelung slinki.

The speed of the wave is 5 m/s. What is the frequency of the wave?
Kelajuan gelombang ialah 5 m/s. Berapakah frekuensi gelombang itu?

A.  1.25 Hz
B.  25Hz
C. 125 Hz
D. 150 Hz



Solution:

Firstly, find the wavelength of the wave. Wavelength is the distance between two successive compression or rarefaction in the slinky roll.

From the diagram 1,  there are 4 successive rarefaction within the 20 cm. Therefore there are four wavelength within the 20 cm.

4λ=20 cmλ=204=5cm

 Hence, wavelength = 5 cm.

Use formula:  Velocity (v) = f ( frequency) x (wavelength)

      5m/s      =  f   x   5/100 ( changing the unit for 5 cm to metre)
           f       =  5  x 100/5
                   = 25 Hz

The answer is B.