Question

In deep water, a tsunami moves very fast and has a long wavelength and a small amplitude (see A in picture). As it enters shallower water, it slows down, and the wavelength decreases. This causes the wave to become much taller (see B in picture).As waves slow down, they start to bunch together, so they have a shorter wavelength than before. This can also be explained by the wave equation v = f x λ (speed = frequency x wavelength), which shows that, when a wave’s speed decreases, it must have a shorter wavelength than before – slowing down won’t change the wave’s frequency.Having a shorter wavelength means that the waves get higher. You could think of the shortened wave as being ‘squashed’ sideways – the water in the wave has to get higher because there’s not as much room for it within the shorter wavelength. It’s a bit like squeezing a toothpaste tube – all the toothpaste is forced upwards.

Answer 1

Given:

The wavelength of the wave decreases as it gets closer to the shore.

The speed of the wave decreases as it gets closer to the shore.

The waves get taller as it gets closer to the shore.

To find:

How does a change in velocity cause a change in amplitude?

Step-by-step explanation:

The amplitude of a wave is described as the distance of the highest point of vibration or the oscillation of the wave from its mean position.

Given that as the velocity of the speed decreases the waves get taller. That is as the velocity decreases the distance of the highest point of vibration of the wave from its equilibrium or mean position increases.

Final answer:

Thus as the velocity of the wave decreases, its amplitude increases.