A race dog is initially running at 10 m/s but is slowing down. How fast is the dog moving when its kinetic energy has been reduced by half? A boulder with a mass of about 1.5 x10^5 kg falls and strikes the ground at 70 m/s. How much kinetic energy does the boulder deliver to the ground? in joules

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.)