6. A ball has mass 0.2 kg and is dropped from a tall tower and falls downward in the positive direction. We assume that the forces acting on the body are the force of gravity and a retarding force of air resistance with direction opposite to the direction of motion and with magnitude cv(t) where c has units of # and v(t) is the S 9.8. Find the velocity of the ball in meters per second (mps) at time t. The gravitational constant is g = value of c if the terminal velocity is 40 mps, and write the differential equation that describes the velocity at time t.