来个英文物理高手解决这选择题目啊~~~!!!!!~~~~!!!!!!!

来源：百度知道 编辑：UC知道 时间：2024/06/20 04:58:40
1.An eagle is flying due east at 8.9m/s carrying a gopher in its talons. The gopher manages to break free at a height of 12m. What is the magnitude of the gopher's velocity as it reaches the ground? Note: effects of air resistance are not included in this calculation.

a)22m/d
b)18m/s
c)11m/s
d)9.8m/s
e)8.9m/s

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题目大意：一只鹰抓着一只地鼠以8.9m/s的速度往东飞。这只地鼠在离地面12m的地方挣脱了。问它落地时的速度是多大？注：不考虑空气阻力

要算落地时的合速度,g取10
水平方向分速度始终为8.9m/s
竖直方向分速度：gt*t/2=12
t=1.55s
竖直方向分速度就等于gt=15.5m/s
再算和速度约等于18
选b

B

v垂直=（2*g*h）^0.5=（2*9.8*12）^0.5=15.34m/s
v水平=8.9m/s
v总=17.73m/s
答案选b