# Homework Help: Speed of falling object via derivation/integration

1. Aug 30, 2010

### warfreak131

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

A stone is dropped from rest at an initial height h above the surface of the earth. Show that the speed with which it strikes the ground is v=sqrt(2gh)

2. Relevant equations

3. The attempt at a solution

I'm just not sure where to get started. I fully understand how to integrate/derive. I am having trouble understanding what equations to start with.

EDIT: I assume that I have to derive/integrate somewhere. I understand how to get sqrt(2gh) just by re-arranging the equation vf2 = vi2+2gh

2. Aug 30, 2010

### rock.freak667

Assuming no air resistance, then the resultant force acting on the mass m is ma=mg.

You can write 'a' as 'dv/dt' and integrate.

Though using kinematics/energy is much simpler.

3. Aug 30, 2010

### warfreak131

that would give me dv/dt = g. if i integrate with respect to t, id get v=gt

edit: nevermind, i got it,thanks