The figure above shows an airplane moving horizontally with a constant velocity of + 115 m/s at an altitude of 1050 m. The directions to the right and upward have been chosen as the positive directions. The plane releases a ‘care package’ that falls to the ground along a curved trajectory. Ignoring air resistance, determine the time required for the package to hit the ground.
由于是二维的运动；所以在求x，y方向的共同变量t时，既可以选择根据x方向的变量计算，也可以根据y方向的变量计算。
而这道题目在y方向的变量更简化：
Voy = 0 m/s; Vy = ?; Y = - 1050 m; ay = - 9.80 m/s*s
根据公示 Y = Voy * t + 1/2 * ay * t*t
最终可以计算出 t ＝ 14.6 s