Question 118779
I stand on a building, 96 feet high. I throw a ball upward at an initial velocity of 80 feet per second. How long will it take for the ball to reach me and how long will it take for the ball to reach the ground?
:
The first situation where it comes back to where it started:
-16x^2 + 80x = 0
Simplify and change the signs, divide equation by -16x:
-16x(x - 5) = 0
Two solutions
-16x = 0
x = 0; where the ball started
and
x = 5 seconds for the ball to return to you
:
The second situation where the ball falls an additional 96 ft to the ground
-16x^2 + 80x + 96 = 0
:
Simplify again divide equation by -16
x^2 - 5x - 6 = 0
Factors to:
(x-6)(x+1) = 0
:
x = +6 seconds to reach the ground
:
A graph where y = height in ft and x = time in seconds, looks like this:
{{{ graph( 300, 200, -4, 8, -20, 200, -16x^2+80x+96) }}}
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Note where time = 0 you are at 96 ft, it returns to the same level in 5 sec and
takes 1 more second to reach the ground.
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