Question 1194516: A rock is dropped off a cliff 115 m high, how long does it take for the rock to reach the ground?
Answer by math_tutor2020(3817)   (Show Source):
You can put this solution on YOUR website!
The meters version of the free-fall formula is this approximate equation
y = 4.9x^2
where,
x = elapsed time in seconds
y = vertical distance traveled in meters
We will ignore air resistance because it greatly complicates the problem.
We are given that the height is 115 meters, so this is the vertical distance needed to hit the ground.
We'll plug in y = 115 and use this to find x. Keep in mind that x > 0.
y = 4.9x^2
4.9x^2 = y
4.9x^2 = 115
x^2 = 115/(4.9)
x = sqrt( 115/(4.9) )
x = 4.84452141651804
x = 4.84
Round the approximate value however you need.
Answer: Approximately 4.84 seconds
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