SOLUTION: A boy steps off a 17.6 foot high diving board with no initial vertical velocity, obeying the law h=-16t^2+vt+s where v is the velocity, t is in seconds, and so is the initial h

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Question 809982: A boy steps off a 17.6 foot high diving board with no initial vertical velocity, obeying the law
h=-16t^2+vt+s
where v is the velocity, t is in seconds, and so is the initial height.
How long does it take him to hit the water?
Answer in units of sec
If, instead, he springs off the diving board
with an initial vertical velocity of 6.7 ft/s,
how long does it take him to hit the water?
Answer in units of sec
How do you go about doing this problem ? I'm pretty confused. Thanks for any help. Much is appreciated.
Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
You can put this solution on YOUR website!
A boy steps off a 17.6 foot high diving board with no initial vertical velocity, obeying the law
h=-16t^2+vt+s
where v is the velocity, t is in seconds, and s is the initial height.
How long does it take him to hit the water?
If he just steps off the diving board there is no upward velocity so the equations is just:
-16t^2 + 17.6 = 0
-16t^2 = -17.6
t^2 = %28-17.6%29%2F%28-16%29
t^2 = +1.1
t = sqrt%281.1%29
t = 1.05 sec to hit the water
:
If, instead, he springs off the diving board
with an initial vertical velocity of 6.7 ft/s,
how long does it take him to hit the water? Now the equation is:
-16t^2 + 6.7s + 17.5 = 0
Use the quadratic formua to find t
I got a positive solution of
t = 1.28 seconds