A student used a spreadsheet to create a computational model of the energy changes experienced by a falling 0.75-kg ball. The student entered a particular initial velocity into the model and noticed that some of the values in the velocity column were positive and some of the values were negative. In one or two sentences, make and justify a claim about the boundary conditions that would lead to this situation.

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.)