Energy Calculations 1 kW = 1,000 watts 1 Hour = 3,600 seconds 1kW = 1000 Joules/s 1 Joule/second = 1 Watt 1 Watt hour = 60 Joules Therefore 1kWh = 3,600,000 Joules

1 kW = 1,000 watts 1 Hour = 3,600 seconds 1kW = 1000 Joules/s 1 Joule/second = 1 Watt 1 Watt hour = 60 Joules 1kWh = 3,600,000 J The turtle has a 60 W heat lamp. If it runs for 10 hours each day how many Joules are used in 2 weeks? 60 J/s ( 10h/day)(7 days/week)(2 weeks)(3600s/h)= 30,240,000J Convert this to kWh. 30,240,000J ( 1 kWh/3,600,000 J ) = 8.4 kWh Find the operating cost for 2 weeks. Cost is $.0758/kWh $.0758/kWh (8.4 kWh) = $ 0.64

1 kW = 1,000 watts 1 Hour = 3,600 seconds 1kW = 1000 Joules 1 Joule/second = 1 Watt 1 Watt hour = 60 Joules 1kWh = 3,600,000 J Assume you use a space heater for a total of 50 days/yr, 10 hours per day, at a rate of 2 kWh per hour. Assume the cost per kWh is $.082 and 1 kWh = 3400 BTUs. Calculate the total number of kWh used per year. 50 days/yr (10 h/day) (2.00 kWh/h) = 1,000 kWh Determine the cost 1,000 kWh/yr ( $.082/ kWh) = $82.00/yr How many BTUs are used in one year? 1,000 kWh/yr (3400 BTUs/ 1 kWh) = 3,400,000 BTUs/yr