How does energy travel in a mechanical wave?

in space

in a vacuum

in a medium

in time

i think c

Asimply means that over time there was some sort of change.

What is the measurement of how fast an object moves relative to a reference point?

When a vertical beam of light passes through a transparent medium, the rate at which its intensity i decreases is proportional to i(t), where t represents the thickness of the medium (in feet). in clear seawater, the intensity 3 feet below the surface is 25% of the initial intensity i0 of the incident beam. what is the intensity of the beam "10" feet below the surface? (give your answer in terms of i0. round any constants or coefficients to five decimal places.)