## freely falling bodies

1. The problem statement, all variables and given/known data

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?

2. Relevant equations
i dont know.

3. The attempt at a solution
vi=0, d=18m, g=9.81, this is all i know.
 PhysOrg.com science news on PhysOrg.com >> Galaxies fed by funnels of fuel>> The better to see you with: Scientists build record-setting metamaterial flat lens>> Google eyes emerging markets networks

Recognitions:
Homework Help
 Quote by mandaa123 1. The problem statement, all variables and given/known data 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? 2. Relevant equations i dont know. 3. The attempt at a solution vi=0, d=18m, g=9.81, this is all i know.
http://www.physicsforums.com/showpos...63&postcount=2