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Question 823156: A ball is thrown upward from the top of a building 100 feet high with initial speed 20 ft/sec. The ball hits the ground after...
Answer by TimothyLamb(4379)   (Show Source):
You can put this solution on YOUR website! ---
equation of ballistic motion:
h(t) = -1/2gt^2 + v0t + h0
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on planet earth at the surface of the planet:
h(t) = -16t^2 + v0t + h0
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for this problem:
h(t) = -16t^2 + 20t + 100 = 0
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the above quadratic equation is in standard form, with a=-16, b=20, and c=100
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to solve the quadratic equation, by using the quadratic formula, copy and paste this:
-16 20 100
into this solver: https://sooeet.com/math/quadratic-equation-solver.php
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this quadratic has two real roots (the x-intercepts), which are:
t = -1.95194102
t = 3.20194102
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negative time doesn't make sense for this problem, so use the positive root
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answer:
the ball hits the ground about 3.2 seconds after being thrown
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Solve and graph linear equations:
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Solve quadratic equations, quadratic formula:
https://sooeet.com/math/quadratic-formula-solver.php
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Solve systems of linear equations up to 6-equations 6-variables:
https://sooeet.com/math/system-of-linear-equations-solver.php
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