SOLUTION: The time in seconds it takes for an object to fall from rest is given by t = 1/4squared s, in which s is the distance fallen. What is the time it takes an object to fakk from a bui

Algebra ->  Algebra  -> Radicals -> SOLUTION: The time in seconds it takes for an object to fall from rest is given by t = 1/4squared s, in which s is the distance fallen. What is the time it takes an object to fakk from a bui      Log On

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Question 120492: The time in seconds it takes for an object to fall from rest is given by t = 1/4squared s, in which s is the distance fallen. What is the time it takes an object to fakk from a building 1400 feet high? I have tried 1/4 the distance fallen squared, and I just don't know how to figure this one out in seconds?
Answer by solver91311(12126) About Me  (Show Source):
You can put this solution on YOUR website!
Your formula is incorrect.

If you drop an object from a fixed height, s, the height, h, of the object after t seconds is given by h=-16t%5E2%2Bs. You want the time it takes for the object starting at 1400 feet to hit the ground, or when h = 0, so:
0=-16t%5E2%2B1400

16t%5E2=1400

t%5E2=1400%2F16

t=sqrt%281400%2F16%29

t=sqrt%281400%29%2F4

t=%285%2Asqrt%2814%29%29%2F2, roughly 9 and 1/3 seconds.

In general, if you drop an object from height s in feet and you want to know the time it takes to reach height h in feet, it takes:

t=sqrt%28s-h%29%2F4 seconds.

Also, if the heights are given in meters, then the constant factor is different:

h=4.9t%5E2%2Bs, so

t=sqrt%28%28s-h%29%2F4.9%29

Hope that helps
John