SOLUTION: A coin is tossed downward with an initial velocity of 30 m/sec from an altitude of 75m. Approximately how long does it take the ball to reach the ground? use 4.9t^2+v0t=s

Question 1061530: A coin is tossed downward with an initial velocity of 30 m/sec from an altitude of 75m. Approximately how long does it take the ball to reach the ground? use 4.9t^2+v0t=s
Answer by Alan3354(69443) (Show Source): You can put this solution on YOUR website!
A coin is tossed downward with an initial velocity of 30 m/sec from an altitude of 75m. Approximately how long does it take the ball to reach the ground? use 4.9t^2+v0t=s
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Coin or ball, either way.
Use + for height and + for ascending.
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Use s(t) = -4.9t^2 + vot + h Where vo is + upward and negative downward & h = 75.
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s(t) = -4.9t^2 - 30t + 75 = 0
s(t) = 0 at impact
-4.9t^2 - 30t + 75 = 0

Solved by pluggable solver: SOLVE quadratic equation (work shown, graph etc)

Quadratic equation (in our case ) has the following solutons:

For these solutions to exist, the discriminant should not be a negative number.

First, we need to compute the discriminant : .

Discriminant d=2370 is greater than zero. That means that there are two solutions: .

Quadratic expression can be factored:

Again, the answer is: -8.02884140597473, 1.90639242638289. Here's your graph:

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Ignore the negative solution
t =~ 1.906 seconds

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