10. On a bus traveling north at 20.0 m/s, a child stands up and walks toward the back of the bus at 1.3 m/s. What is the child's resultant velocity?
18.7 m/s north
21.3 m/s north
18.7 m/s south
21.3 m/s south

How does the kinetic energy of a charge change as the charge moves under the effect of an electric field from higher potential to lower potential? a.the kinetic energy increases.b.the kinetic energy decreases.c.the kinetic energy remains the same.d.the kinetic energy is always zero.

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.)

Give one example to show that when substances are mixed,it may result in a chemical or a physical change depending on the conditions.