(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

In an over hand serve, the ball starts from a point 2m above the ground and travels a horizontal distance of 20m before it strikes the floor.

The ball travels in a parbolic path and reaches its highest point after travelling a horizontal distance of 9m as show in the link below:

http://img407.imageshack.us/my.php?image=asdaq2.jpg

http://img407.imageshack.us/img407/7919/asdaq2.jpg [Broken]

http://g.imageshack.us/img407/asdaq2.jpg/1/ [Broken]

Determine the equation of the parabola in the form y-k=a(x-9)^2

2. Relevant equations

y-k=a(x-h)^2

3. The attempt at a solution

Well i know that the ball reaches its maximum height 9 feet from

where it was served. If we let x=0 be where the ball was served,

then we know the x coordinate of the vertex is 9, so the equation is

of the form

y-k=a(x-9)^2

To finish the equation precisely, I need to determine the values of

a and k. To do that, I need two equations relating the values of a

and k. But the given information provides with what I need to

write those two equations --I know the x and y values (1) where

the ball was served and (2) where it hit the ground.

but i'm still confused ! i could use some help:)

could somebody solve it for mee pleaaase??

**Physics Forums | Science Articles, Homework Help, Discussion**

Dismiss Notice

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Homework Help: Help with parabola

**Physics Forums | Science Articles, Homework Help, Discussion**