懂英文的进.
问题描述：
懂英文的进.
A light is at the top of a pole 80ft high.A ball is dropped at the same height from a point 20ft from the light.Assuming that the ball falls according to the law s=16t^2,how fast is the shadow of the ball moving along the ground one second later?
答案是200ft/sec.
答
XXV2008 ,中文意思如下：灯在一个高80英尺的竿的顶端,一个在竖直位置与灯同高,水平方向距灯20英尺的点落下,假定灯以s=16t^2（s为距离,t为下落时间）的规律下落,请问,1秒后灯的影子沿地面移动的速度是多少?楼主,你画...