Question

if a wave were nine feet high how much would the amplitude be?

Answer 1

-9 would be the answer but i also need more information

Answer 2

The answer would be:

4.5 ft

Here's why:

Amplitude is defined as the distance between the crest/trough of a wave to the midline or the resting point. When you say the height of the wave, you are talking about the distance from the crest and the trough.

The amplitude would then be half of the wave height. Since the wave height in this scenario is 9 ft then we just divide that by 2.

$\dfrac {9ft}{2} = 4.5 ft$

You can refer to the attachment below to see the different properties of a wave. (Image is not mine)