Answer:
T = 2.57 s
Step-by-step explanation:
The period of a wave is equal to the time it takes for one wavelength to pass by a fixed point.
No of waves observed = 10.9
Time taken, t = 28 s
We need to find the period of the water waves. Number of waves per unit time is called frequency. Let it is f. So,
![f=(n)/(t)\\\\f=(10.9)/(28)\\\\f=0.389\ Hz](https://img.qammunity.org/2021/formulas/physics/college/qbhrb5tf1pvu4gfxyoiip26klu77r9mj48.png)
If T is period of the wave. It is equal to the reciprocal of frequency.
![T=(1)/(f)\\\\T=(1)/(0.389)\\\\T=2.57\ s](https://img.qammunity.org/2021/formulas/physics/college/2ljlqk8a0rdwmh5jznzggn867m0omzm3vu.png)
So, the period of the water waves is 2.57 seconds.