16.

Two horizontal forces, F, and F, are acting on a box, but only F, is shown in the drawing. F, 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, = +4.2 N and the mass of the box is 3.9 kg. Find the magnitude and direction of F, when the acceleration of the box is (a) +7.9 m/s?. (b) -7.9 m/s?. and (c) Om /s?. (a) (b) (c) Fi .A 1940-kg car is traveling with a speed of 13.6 m/s. What is the magnitude of the horizontal net force that is required to bring the car to a halt in a distance of 68.1 m? Number i UnitsTwo forces FA and FB are applied to an object whose mass is 12.6 kg. The larger force is FA. When both forces point due east, the object's acceleration has a magnitude of 0.427 m/s2. However, when F, points due east and FR points due west, the acceleration is 0.374 m/s2, due east. Find (a) the magnitude of FA and (b) the magnitude of FB. (a) Number i Units (b) Number i Units