2. 1 Calorie : energy needed to heat 1 g of water by 1 o C 1 Calorie = 4.182 Joules ≈ 4.200 J 1 C (or food calorie or KILO calorie) = 4200J BTU (British Thermal Unit) Energy needed to heat 1 lb of water by 1 o F… 1 BTU = 1055 Joules ≈ 1 kiloJ

3. Guess: how much energy is there in a pound of an explosive, such as dynamite or TNT, compared to, say, a pound of chocolate chip cookies? Object Energy in one gram Compared to TNT Calories Joules Bullet (moving at speed of sound) 0.01 40 0.015 Battery (flashlight) 0.01 40 0.015 Battery (computer) 0.1 400 0.15 TNT (trinitrotoluene) 0.651 2723 1 Modern High Explosive (PETN) 1 1.6 Chocolate Chip Cookies 5 21 kJ 8 Butter 7 29 kJ 11 Gasoline 10 42 kJ 15 Methane gas (CH 4 ) 13 54 kJ 20 Hydrogen gas (H 2 ) for fuel cell 26 110 kJ 40 Asteroid or meteor (30 km/sec) 107 450 kJ 165 Uranium-235 20 million Ca l84 billion J 30 million http://muller.lbl.gov