The Gateway Arch in St. Louis is 640 ft high. How long would it take an object to fall freely from the top?

Question

anonymous · Answer

Do we know anything about the object like weight?

anonymous · Answer

we don't need

anonymous · Answer

acceleration of free fall (a) = 9.8m/s²
distance (s) 640ft = 195m
initial velocity (u) = 0m/s
we need time (t)

Now use the kinematics equation: s = ut + 1/2at²

This is actually a physics question

anonymous · Answer

The function st  16t2
 is used to approximate the distance s, in feet, that an object falls freely from rest
in t seconds.

anonymous · Answer

what is the function? st 16t2?

anonymous · Answer

s(t)=16t^2

anonymous · Answer

Well then, there you have it. I guess that's how it is in ft. Never worked in US units before, so can't say.

s = 16t²
640 = 16t²

solve for t