# A block of ice falls and a part melts

1. Aug 26, 2010

### Karol

$$\cdot$$1. The problem statement, all variables and given/known data
A block of ice falls into a lake who's temperature is 00c.
Half of a percent of it's mass melts. What is the minimum height the block falls from.

2. Relevant equations
The Latent heat of water:L=79.7[Cal/gr]
Potential energy: EP=mgh

3. The attempt at a solution
the potential energy of the block transforms into heat which melts the ice.
I'm using L, the latent heat in [Cal/Kg] in order to be in the SI unit system and get the height h in meters:
mgh=79,700$\cdot$0.005$\cdot$m
$\Rightarrow$h=40[m]
The answer should be 171[m], according to the book.

2. Aug 26, 2010

### kuruman

The SI unit for latent heat is Joules/kg not cal/kg.