# An object is dropped from the top of building that is 200 feet about ground level. When object will reach ground ?

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Expert Answers

nathanshields | Certified Educator

Use acceleration due to gravity: g = -32ft/sec^2, initial velocity of 0, and initial height of 200 in the equation:

`h(t) = -1/2 g t^2+v_0t+h_0`

So we have

`h(t)=-16t^2+200`

Solve for t when h(t) = 0:

`-200 = -16t^2`

`200/16 = 100/8 = 50/4 = 25/2 = t^2`

t = 3.5 seconds.