To calculate the average deceleration while a person is under the water, we need to know the initial velocity, final velocity, and the time taken for deceleration.
Let's assume the person is initially moving with a velocity v0, and they come to a stop in a distance d underwater. We also need to know the time taken for this deceleration, denoted as t.
The average deceleration (a) can be calculated using the formula:
a = (v - v0) / t
where v is the final velocity, which is 0 since the person comes to a stop.
Since we don't have specific values for v0, v, and t, we cannot provide a numerical answer. However, if you provide the required values, I would be able to calculate the average deceleration for you.