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AGC/United Learning • 1560 Sherman Ave., Suite 100 • Evanston, IL 60201 • 800-323-9084

THAT’S THREE MAJOR ENERGY CONVERSIONS: ELECTRICAL POTENTIAL TO ELECTRICAL, TO THERMAL, TO SOUND. AS A RESULT, 75% OF THE LIGHTNING BOLT’S ORIGINAL ENERGY GETS TRANSFERRED TO THE AIR, WHILE 25% MAKES IT TO THE GROUND. OF COURSE, 5 MEGAJOULES IS STILL A LOT OF ENERGY...IF ONLY WE COULD HARNESS IT. SARAH: THIS IS A WALNUT. IT CONTAINS STORED CHEMICAL ENERGY. THE TREE THAT PRODUCED IT CAPTURED ENERGY FROM THE SUN AND, THROUGH THE PROCESS OF PHOTOSYN- THESIS, STORED SOME OF THAT ENERGY IN THE NUT. WHEN WE EAT ANY FOOD, OUR BODIES TRANSFORM THE STORED CHEMICAL ENERGY INTO ELECTRICAL ENERGY FOR OUR NERVES, THERMAL ENERGY LIKE BODY HEAT, AND KINETIC ENERGY FOR MOTION. WE CAN CALCULATE THE EFFICIENCY OF THESE CONVERSIONS BY TAKING THE USEFUL ENERGY OUTPUT AND DIVIDING IT BY THE ENERGY INPUT. LET’S TAKE A LOOK AT TWO WAYS TO FIGURE OUT HOW MUCH ENERGY IS STORED IN THIS NUT. THEN WE’LL COMPARE THE METHODS. LAUREEN: SO WE’RE TRYING TO FIND OUT HOW MUCH EN- ERGY IS STORED IN A WALNUT. BRENDON: AND THEN COMPARE THE RESULTS WE GET, WITH WHAT A TECHNICIAN IN A HIGH-TECH LAB GETS. LAUREEN: YEAH, BUT RIGHT NOW THE ENERGY IS STORED AS CHEMICAL POTENTIAL ENERGY — SOMETHING WE CAN’T MEASURE. BRENDON: SO WE HAVE TO CONVERT THE POTENTIAL ENERGY INTO A FORM WE CAN MEASURE, LIKE THERMAL ENERGY. LAUREEN: WE CAN DO THIS BY USING A CALORIMETER AND THE EQUATION: Q EQUALS MC DELTA T. I’VE GOT THE EQUA- TION, BUT NO CALORIMETER. BRENDON: HOW ABOUT...A TEST TUBE AND A THERMOMETER? LAUREEN: WORKS FOR ME. WE’LL ALSO NEED SOME ALUMI- NUM FOIL, A BALANCE, LIGHTER, A CANDLE, A RETORT STAND, AND THOSE CLAMPS. REMY ESTIGOY: ONE OF THE ANALYSIS THAT WE DO IN THIS LAB IS TO FIND OUT THE ENERGY CONTENT OF COAL SAMPLES OR OIL SAMPLES. TO DO THAT WE USE THE BOMB CALORIM- ETER. IT’S CALLED THE “BOMB CALORIMETER” BECAUSE THE

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