Figure 11 shows a large tank of water - Edexcel - GCSE Physics - Question 6 - 2020 - Paper 1

The wavelength can be calculated using the formula:

$\text{Wavelength} = \frac{\text{Distance from L to M}}{\text{Number of wavelengths}}$

Given that the distance is 32 m:

$\text{Wavelength} = \frac{32 m}{10} = 3.2 m$

Frequency is calculated using the formula:

$\text{Frequency} = \frac{\text{Number of waves}}{\text{Time}}$

Substituting the values:

$\text{Frequency} = \frac{12}{15 s} = 0.8 (Hz)$

The arrows should show movement in the direction of the wave propagation, with one arrow moving to the right and one to the left, indicating that the rock at R oscillates back and forth.

Using the equation:

$\text{Wavelength} = \frac{\text{Wave speed}}{\text{Frequency}}$

Substituting in the values:

$\text{Wavelength} = \frac{7000 m/s}{12 Hz} = 583.33 m$

Rounding to a valid format, the wavelength is approximately 580 m.

Counting waves directly is not suitable for seismic waves because:

1. Seismic waves are often not visible on the surface upon arrival, making counting difficult.
2. A technician would require an accurate method, as they cannot rely on fast counting due to the rapid arrival of waves.
3. The frequency of seismic waves might be too high to accurately count within the observed time frame.