A batter swings a bat so it is moving in the -z direction when it makes contact with a 0. 145 kg baseball moving about 77 mph in the +z direction. After the contact the ball ends up traveling in the -z direction. From slow-motion videos, we are able to estimate that the ball is in contact with the bat for about 1.2 milliseconds (1.2 x 10 3 s). From other measurements we find that the force exerted by the bat on the ball is (0, 0, - 1.30 x 104) N