Question

In a cabin sauna, 85 l of lake water at a temperature of +7°C is heated in an iron pot of 29
kg. The water temperature must be +86°C. The temperature of the iron pot is +12 °C before
the water is poured in. The water is heated by fire wood and 65 % of the thermal energy
released in combustion is wasted. The heating value of the fire wood (thermal energy
released in combustion of one kilogram) is 12 MJ/kg. How much fire wood is needed to heat
the water? The specific heat capacity of iron is 473 J/kg°C, and the specific heat capacity of
water is 4190 J/kg°C. Give the answer in 0,1 kg precision.

Answer 1

.....thats over my head. When I was in charge of the scout troop we just got some wood togther and built a campfire :)