Question 1916: Lucy tosses a ball up to Carry, waiting at a third-story window, with an initial velocity of 30 feet per second. She releases the ball from a height of 6 feet. The equation h=-16t^2+30t+6 represents the height, h, of the ball after t seconds. If the ball must reach a height of 25 feet for Carry to catch it, does the ball reach Carry? Explain.
(Hint: Substitute 25 for h and use the discriminant.)
Answer by longjonsilver(2297)   (Show Source):
You can put this solution on YOUR website! if i understand correctly, the ball is thrown in an arc by Lucy, from the ground, with the ball starting at 6 feet from the ground.
I take it h is the height from ground level rather than from where the ball started its flight.
What you need to do is let h=25, as you say, and the re-arrange the equation to have everything on one side, so it all equals zero. Then put the numbers into the quadratic formula, where you will find that the square root is of a negative number. This means here that the ball does not reach 25 feet up, so Carry cannot catch it.
You put the numbers in and confirm my story.
jon.
|
|
|
