How Much Warmer Could Water Get After a 50 Meter Fall?

[caesius]

Homework Statement

On his honeymoon, James Joule tested the conversion of mechanical energy into internal energy by measuring temperatures of falling water. If water at the top of a Swiss waterfall has a temperature of 10.0 degrees Celsius and then falls 50.0 m, what maximum temperature at the bottom could Joule expect?

Homework Equations

change in internal energy = mgh

The Attempt at a Solution

I'm sure this question is easy I must be missing something, the change in internal energy is mgh but we have no mass?

The answer is (10.0 + 0.117) but I don't see how this was found.

 

[olgranpappy]

use
$$\Delta E = c M \Delta T$$
where c is the specific heat. the mass drops out.