Calculating the Velocity of a Rock Thrown from a Building Roof

[magasiki]

A rock is thrown from the roof of a building with a velocity v_0 at an angle of alpha_0 from the horizontal. The building has height h. You can ignore air resistance.

Calculate the magnitude of the velocity of the rock just before it strikes the ground.

Homework Equations

V=V_0 + at
X=V_0t + 1/2at^2

The Attempt at a Solution

v_0(sin(alpha_0))-2(v_0)
The catch is that when i put the answer into the system, it told me that v_o and alpha_0 are not part of the answer. Any help is appreciated.

 

[cristo]

Well, there are other kinematic equations, and I presume you would need to use the height, so look into the equations involving height. Do you know what constants the answer should be expressed in?

 

[arildno]

Or, don't bother about sub-equations at all!

Instead:
What is the FUNDAMENTAL equation of motion valid for ALL CLASSICAL PHYSICS PROBLEMS?

 

[kser]

I also need help with this... is the equation you're talking about v = x/t?