Aseaplane of total mass m lands on a lake with initial speed viî. the only horizontal force on it is a resistive force on its pontoons from the water. the resistive force is proportional to the velocity of the seaplane: r = −bv. newton's second law applied to the plane is −bvî = m(dv/dt)î. from the fundamental theorem of calculus, this differential equation implies that the speed changes according to