Two horizontal forces, F, and F,, are acting on a box, but only F, is shown in the drawing. E, can point either to the right or to the left. The box moves only along the x axis. There is no friction between the box and the surface. Suppose that F, = +4.8 N and the mass of the box is 5.0 kg. Find the magnitude and direction of F, when the acceleration of the box is (a) +7.7 m/s2, (b) -7.7 m/s?, and (c) 0m/s2. +.x