kilocalories The enorgy needed to keep a 75 -watt lightbulb Express your answer using two significant figures. burming for 1.0h is 270kJ. Calculate the energy , required to keep the lighibulb burning for 5.0h in each of the tollowing energy units. The energy needed to keep a 76-watt lightoulb 'buming for 1.0h is 270kJ. Calculate the energy Express your answer using two significant figures. required to keep the lightbulb burning for 5.0h in each of the lollowing energy units