Finding max. height of object thrown vertically upard

[chuntaro]

Homework Statement

An object is thrown vertically upward such that it has a speed of 47 m/s when it reaches two thirds of its maximum height above launch point. Find maximum height h.

Homework Equations

V^2-Vo^2 = 2gh
or
V^2-Vo^2 = 2g(1/3H)?

The Attempt at a Solution

Final velocity= 0 m/s
Velocity at 2/3h= 47 m/s
Acceleration of gravity=9.8 m/s^2

 

[thebigstar25]

dont confuse yourself .. You can solve the following equations to get the max. Height :

(47)^2 - vo^2 = 2g(2/3) ymax
0 - vo^2 = 2g ymax

You can as a start subtract the second equation from the first .. And keep in mind that you are using g as a vector not a scalar value in that equation ..