2001年9月11日,美国标志性建筑--世贸大厦受到恐怖袭击而倒塌,

2001年9月11日,美国标志性建筑--世贸大厦受到恐怖袭击而倒塌,造成了重大伤亡,据说,当时有人情急之下纵身从楼上跳下,假设有人从21楼跳下(设每层楼高4M,跳离楼后做自由落体运动),求:
(1)该人的落地速度多大?(g=10m/s2
(2)该人在下落过程经历的时间。

答案

20m/s ; 50m

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