SOLUTION: set h=0Trying to solve this multiple part problem, I have tried using the quadratic equation, I don't think I'm putting the numbers in the right place. I know the formula for heig

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Question 596212: set h=0Trying to solve this multiple part problem, I have tried using the quadratic equation, I don't think I'm putting the numbers in the right place. I know the formula for height, not sure where to start.
Here's the problem: Guns on a battleship must fire their charges many miles. In order to do this the charge must be fired high up into the sky. Suppose that one such gun shoots a charge so that its initial height above the water is 50 ft and its initial upward velocity is 1000 ft/ sec.
1. How many seconds after it was shot will the charge hit the ocean?
2. Fifty seconds after being fired, how high above the water will the charge be?
3. How many seconds after it was shot will the charge first be 2000 ft high?
4. How many seconds after it was shot will the charge next be 2000 ft high?
5. What is the maximum height that the charge will reach?
6. How high above the water will the charge be in 10 seconds?
Answer by scott8148(6628) (Show Source):
You can put this solution on YOUR website!
(height) = -(half the gravitational acceleration times the time squared) + (initial velocity times the time) + (initial height)

h = -16t^2 + 1000t + 50

the max height is on the axis of symmetry ___ t = -1000 / [2(-16)] = 125/4
___ substitute the time into the equation to find the height

the quadratic formula is ___

remember that the equation must equal zero to use the formula
___ you may have to subtract the height from the expression to accomplish this

1. set h=0 in height equation, use quadratic formula to solve

2. (and 6) plug time into height formula

3. (and 4) height is 2000, but equation must equal zero to use quadratic formula (see above comments)

5. see above comments