关于美国高中代数的题目希望回答的时候也是用英文.可以用翻译器~ />

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关于美国高中代数的题目

希望回答的时候也是用英文.可以用翻译器~  />

When t is 0,H = -16t² + h = -16*0² + 30 = 30 ft (30 feet higher than the ending point,the lower cliff)
When the vehicle reaches the lower cliff,H = -16t² + 30 = 0
t = √30/4
During this period (√30/4 seconds),the vehicle must travel at least 100 feet horizontally.The speed is 60 miles/hour,which is 60*5280 ft/3600 second
In √30/4 second,the vehicle travels (√30/4)(60*5280/3600) = 120 ft
Which is more than the 100 feet gap,so the batman can reach the lower cliff.

v=5280*60/3600=88feet/s
16*t*t=30 t=sqrt(30)/4
s=v*t=120.5feet>100feet
so t=sqrt(30)/4=1.37s