Question 174143: When a ball is thrown, its height in feet h after t seconds is given by the equation
h=vt-16t^2
where v is the initial upwards velocity in feet per second. If v=15 feet per second, find all values t of for which h=3 feet. Do not round any intermediate steps. Round your answer to 2 decimal places.
Answer by stanbon(75887)   (Show Source):
You can put this solution on YOUR website! When a ball is thrown, its height in feet h after t seconds is given by the equation
h=vt-16t^2
where v is the initial upwards velocity in feet per second. If v=15 feet per second, find all values t of for which h=3 feet.
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h(t) = vt-16t^2
3 = 15t - 16t^2
16t^2 - 15t + 3 = 0
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Use the Quadratic formula to solve for "t":
t = [15 +- sqrt(225 - 4*16*3)]/32
t = [15 +- sqrt(33)]/32
t = [15 + sqrt(33)]/32 = 0.64827 seconds
or
t = [15 - sqrt(33)]/32 = 0.28923 seconds
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Cheers,
Stan H.
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