What are the dimensions of a square that has an area of 4cm^2

On his honeymoon, james joule attempted to explore the relationships between various forms of energy by measuring the rise of temperature of water which had fallen down a waterfall on mount blanc. what maximum temperature rise would one expect for a waterfall with a vertical drop of 20 m? the specific heat of water is 4186 j/kg ∙ k. a)0.064 c° b)0.053 c° c)0.071 c° d)0.047 c°