What Height Does a Ball Reach When Its Speed Halves?

[mandaa123]

Homework Statement

A ball is thrown straight upward and rises to a maximum height of 18 m above its launch point. At what height above its launch point has the speed of the ball decreased to one-half of its initial value?

Homework Equations

i don't know.

The Attempt at a Solution

vi=0, d=18m, g=9.81, this is all i know.

 

[LowlyPion]

Homework Statement

A ball is thrown straight upward and rises to a maximum height of 18 m above its launch point. At what height above its launch point has the speed of the ball decreased to one-half of its initial value?

Homework Equations

i don't know.

The Attempt at a Solution

vi=0, d=18m, g=9.81, this is all i know.

https://www.physicsforums.com/showpost.php?p=905663&postcount=2