SOLUTION: I am looking for help with the following problem: "Cathy hit a golf ball 140 yards down the fairway. If the ball reaches a maximum height of 20 yards, find the equation for the

Algebra ->  Exponential-and-logarithmic-functions -> SOLUTION: I am looking for help with the following problem: "Cathy hit a golf ball 140 yards down the fairway. If the ball reaches a maximum height of 20 yards, find the equation for the      Log On


   



Question 246811: I am looking for help with the following problem:
"Cathy hit a golf ball 140 yards down the fairway. If the ball reaches a maximum height of 20 yards, find the equation for the height of the golf ball verses the distance it has traveled. Assume a parabolic path."
Thank you for your help.

Answer by stanbon(75887) About Me  (Show Source):
You can put this solution on YOUR website!
"Cathy hit a golf ball 140 yards down the fairway. If the ball reaches a maximum height of 20 yards, find the equation for the height of the golf ball verses the distance it has traveled. Assume a parabolic path."
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At time zero the height is zero so the ball starts at (0,0)
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Vertex is (v,20)
x intercept is (140,0) is the point the ball hits the ground.
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The equation of the paratola is
y = k*x(x-140)
y = kx^2 -140kx
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The vertex occurs when v = -b/2a = 140k/(2k) = 70
Vertex is (70,20)
So, 20 = k*70(70-140)
20 = 70k(-70)
20 = -4900k
k = -2/490 = -1/245
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Equation:
y = (-1/245)(x^2-140x)
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graph%28400%2C300%2C-10%2C150%2C-10%2C25%2C%28-1%2F245%29%28x%5E2-140x%29%29
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Cheers,
Stan H.