# A stone is dropped from a window 5m high what is its speed

1. Nov 28, 2007

### indy92

Ok this might be a simple problem but i have no idea how to do it;

A stone is dropped from a window 5m high what is its speed when it hits the ground.

I dont need answer i just need a formula or some guidence
Thanks

Last edited by a moderator: Mar 7, 2013
2. Nov 28, 2007

### rock.freak667

What does the stone have at 5m high?(what kind of energy) when dropped...this kind of energy is converted into energy a body possesses by virtue of its motion...

Law of conservation of energy

3. Nov 28, 2007

### indy92

at 5m it has gravitaitional potential energy and when its is dropped it is converted to kinetic energy
ive got the formula for GPE it is height x weight
and for kinetic energy its 1/2 x mass x speed^2

these might not be the right formulas as i dont have the mass

4. Nov 28, 2007

### rock.freak667

But...weight= mass x accel. due to gravity...so if you equate the two you will get:
1/2 x mass x speed^2= Height x weight

1/2 x mass x speed^2=Height x mass x accel. due to gravity

do you see anything canceling out?

5. Nov 28, 2007

amny thanks