8.13 . A 2.00-kg stone is sliding Figure E8. 13 to the right on a frictionless hori- zontal surface at 5.00 m/s when F(KN ) it is suddenly struck by an object that exerts a large horizontal force on it for a short period of 2.50 time. The graph in Fig. E8.13 shows the magnitude of this force as a function of time. (a) What impulse does this force exert on 15.0 16.0 the stone? (b) Just after the force stops acting, find the magnitude and direction of the stone's velocity if the force acts (i) to the right or (ii) to the left