Question 581420: h=-16t^2+vt+s, where h is the height (in feet), t is the time in motion (in seconds), v is the initial velocity (in feet per second), and s is the initial height(in feet)
A gymnast dismounts the uneven parallel bars at a height of 8 feet with an initial upward velocity of 8 feet per second. Find the time (in seconds) it takes for the gymnast to reach the ground.
Answer by nerdybill(7384)   (Show Source):
You can put this solution on YOUR website! h=-16t^2+vt+s, where h is the height (in feet), t is the time in motion (in seconds), v is the initial velocity (in feet per second), and s is the initial height(in feet)
A gymnast dismounts the uneven parallel bars at a height of 8 feet with an initial upward velocity of 8 feet per second. Find the time (in seconds) it takes for the gymnast to reach the ground.
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from the statement of the problem we have:
v is 8 ft per sec
s is 8 ft
set h to zero (ground) and solve for t:
h=-16t^2+vt+s
0=-16t^2+8t+8
dividing both sides by 8:
0=-2t^2+t+1
multiplying both sides by -1:
0=2t^2-t-1
0=2t^2-2t+t-1
0=(2t^2-2t)+(t-1)
0=2t(t-1)+(t-1)
0=(t-1)(2t+1)
t = {-1/2, 1}
throw out the negative solution leaving:
t = 1 second
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