A 20 kg box has an initial velocity of 2 m/s starting at the bottom of a 30-degree inclined plane. A person pushes on the box directly up the inclined plane so that it travels up the inclined plane at a constant velocity of 2 m/s. If the coefficient of friction is 0.2 and the person pushes hard enough to maintain that constant 2 m/s, calculate how much work is done by the person after 5 seconds have passed

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.)