A wave takes 5 s to complete 10 cycles. Its wavelength is 1.2 m. Calculate (a) frequency and (b) speed.

Solution & explanation

1. Given: cycle count 10, elapsed time 5 s and λ = 1.2 m.

2. Frequency is cycles divided by time.

   $$f=\frac{10}{5}=2$$

3. The result is 2 Hz, meaning two cycles each second.

4. Use the wave-speed relation.

   $$v=f\times \lambda$$

5. Substitute frequency and wavelength.

   $$v=2\times 1.2$$

6. Multiply, retaining m s⁻¹.

   $$v=2.4$$

f = 2 Hz; v = 2.4 m s⁻¹