At time t = 0, a ball is struck at ground level and sent over level ground. The figure below gives the magnitude p of the ball's momentum versus time t during the flight. (p1 = 7.0 kg·m/s and the vertical axis is marked in increments of 0.5 kg·m/s.) At what initial angle above the horizontal is the ball launched? http://www.webassign.net/hrw/W0170-Nalt.jpg I feel like this question is relatively easy, I'm just really stuck for some reason! At the highest point, I know the vertical component of momentum is 0, making the horizontal component 7. I don't know how to find the initial momentum though; I know we can probably find it using the graph (see link), and I found it to be 9.0 kg m/s, and, after I did the math, the computer told me my answer was wrong. Is there something I'm overlooking??