Law of conservation of energy
	• Energy cannot be created or destroyed, only changed in form. The total energy in the universe is a constant. • Energy measured in calories(cal) and joules (J). • 1 cal = 4.184 J and is the amt of heat energy needed to raise the temperature of 1 gram of water by 1 degree C. • Food calorie = 1000 cal or Kcal (kilocalories)