SOLUTION: If a penny is thrown downward at 30 ft/sec from the bridge at Royal Gorge, Colorado, how long does it take to reach the Arkansas River 1000 ft below? It says to use the quadra

Question 209449: If a penny is thrown downward at 30 ft/sec
from the bridge at Royal Gorge, Colorado, how long does it
take to reach the Arkansas River 1000 ft below?
It says to use the quadratic equation.

x^2-〖30〗^2=〖1000〗^2
I have work started but it's not pasting into here.
It's from my online textbook, I cannot find the ISBN.

Answer by Alan3354(69443) (Show Source): You can put this solution on YOUR website!
If a penny is thrown downward at 30 ft/sec
from the bridge at Royal Gorge, Colorado, how long does it
take to reach the Arkansas River 1000 ft below?
It says to use the quadratic equation.
-----------
The height of an object (neglecting air friction) is
h(t) = -16t^2 + vt + h0 Where v is the starting speed and h0 is the initial height. t is in seconds, h in feet.
In this case h0 = 1000 ft, and v = -30 ft/sec (-30 since it's thrown downward)
Find when h(t) = 0
0 = -16t^2 - 30t + 1000
-8t^2 - 15t + 500 = 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=16225 is greater than zero. That means that there are two solutions: .

Quadratic expression can be factored:

Again, the answer is: -8.89858700178562, 7.02358700178562. Here's your graph:

----------
Use the positive value for t (it says x2)

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