Halliday, Resnick & Walker — Center of Mass and Linear Momentum: Problem 20

At time \(t = 0\), a ball is struck at ground level and sent over level ground. The momentum \(p\) versus \(t\) during the flight is given by Fig. 9.24 (with \(p_0 = 6.0 \text{ kg} \cdot \text{m/s}\) and \(p_1 = 4.0 \text{ kg} \cdot \text{m/s}\)). At what initial angle is the ball launched? (Hint: Find a solution that does not require you to read the time of the low point of the plot.)