Brett takes a slap shot, exerting an average force of 16.8 newtons on the puck for 0.116 seconds. The puck has a mass of 0.110 kilograms and was initially moving directly away from the goal at 3.4 meters per second. How fast does it move toward the goal? 21.127 or -21.127 is not the correct answer. I am unsure which direction would be considered negative momentum. Here is my work. Impulse= 1.95 1.95=change in momentum 1.95= mass X change in velocity 1.95= .110kg X (vf-3.4) I divided 1.95 by .110kg and then added 3.4 to the other side. According to my online homework checker this is wrong. Could someone please help me solve this overthought problem? Perhaps something isn't negative when it should be.