The only force acting on a 3.0 kg body as it moves along the positive x axis has an x component Fx = -7x N, where x is in meters. The velocity of the body at x = 2.0 m is 11 m/s.
(a) What is the velocity of the body at x = 4.9 m?
(b) At what positive value of x will the body have a velocity of 4.2 m/s?