# Homework Help: Physics question (kinetic energy) to all that apply

1. Sep 15, 2004

### airkapp

Regarding what formula to use and how exactly is it modified to fit this problem:

A 2.0KG coconut (initially at rest) falls from the top of a coconut tree 15 m high. What is the coconut's kinetic energy when it hits the ground? What is its speed?

I went ahead and drew it out. I'm thinking I can use formulas for potential energy and kinetic. K=1/2 mv^2 and mg(z1-z2); still trying to figure out how to set it up,
Jason

Last edited: Sep 15, 2004
2. Sep 15, 2004

### Pyrrhus

Seems to me like it's a Conservation of Mechanical Energy problem,

Kinetic Energy is always [In Classical Physics] 1/2*m*v^2
Potential Energy here will be from gravity, mgh.

It has two points you can use, when it starts (Vo =0) and when it hits the ground (h=0).

3. Sep 15, 2004

### Sirus

Kinematics formulas will also work. You have initial velocity, acceleration, vertical distance, now find final velocity, then use that to find kinetic energy. Since this is probably in an Energy unit, though, you might want to stick to conservation of mechanical energy. Both methods work.