To prepare a cup of tea of 100ml how many joules of energy are required?
Answers
Energy (heat) in joule’s =mass x c x delta TWhere c = 1200 joule’s per Kg KelvinIn the equation the mass and delta T cancel out the per Kg and the temperature K leaving the answer in Joule's (The unit of power)K equals Kelvin’s that is the total temperature. Still in degrees but where centigrade is -273 degrees C, the temperature in Kelvin is zero. So 0 degrees C is 273 degrees Kelvin.What c in the equation is, the specific heat capacity. So in water it takes 1200 joule's to raise a Kg of water by 1 degree K or in degrees C.So the answer is Delta T equals 20 degree C to 100 degree C presumptuous the water is at room heat. So Delta T =801 liter of water weighs 1 KgSo the heat required is 80 x 1200 x 1 =96000 joule's =96 kilo joulesIf this takes 1 min to simmer the power required to simmer the water colleagues 96kilo joules/60 seconds =1600 watts or 1.6 kilo watts.Dividing this by 60 into minutes and then by 60 again into hours gives the answer in kilo watt hours as what appears on your energy bill. 0.444 kilo watt hours.