u2 g\frac{\mathrm{u}}{2 \mathrm{~g}}2 gu
u2g\frac{u^{2}}{g}gu2
u22 gsinα\frac{\mathrm{u}^{2}}{2 \mathrm{~g}} \sin \alpha2 gu2sinα
2ug\frac{2 u}{g}g2u