fitting) From the curve a value of dQ\dT can be found for any temperature, and the rate of heat loss is mass x specific heat x dQ\Dt. Terry Porritt 01-04-2009, 07:07 AM Whoops, no one spotted the undeliberate mistake or typo. The slope of the cooling curve is dT\dt, so the rate of heat loss from the tank is: mass(of water) x specific heat x dT\dt murphfan51 08-04-2009, 09:12 PM Thanks for that guys. I have showed my boss (as he was asking me if I knew it) but I told him I got it from a person on this site. Thanks:thumbs: