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

BRENDON: SO I JUST PICK A FOOD WITH HIGH ENERGY CON- TENT AND I’M ALL SET. ALYSON LEWIS: WELL, I WISH IT WERE THAT EASY. IT IS POS- SIBLE FOR US TO GO OVER BUDGET. AND THEN WE TEND TO GAIN WEIGHT AS EXCESS BODY FAT. BRENDON: BRINGS A NEW MEANING TO THE TERM “WAIST” ENERGY. ALYSON LEWIS: RIGHT. BRENDON: IT’S STILL JUST A NUMBER TO ME. HOW DO WE USE IT? ALYSON LEWIS: I GUESS THE BEST THING TO DO IS TO DO A COMPARISON. SO LET’S PRETEND WE HAVE A BOWL FULL OF GRANOLA. THAT’S GOING TO GIVE US MORE ENERGY TO OUR BODIES THAN, LET’S SAY, A BOWL FULL OF CRISP RICE. LET’S SAY WE’RE GOING SKIING FOR A DAY. WHICH ONE OBVIOUSLY, THEN, IS GOING TO GIVE US MORE ENERGY FOR THAT ENDUR- ANCE ACTIVITY? BRENDON: I’M A GRANOLA KINDA GUY. ALYSON LEWIS: RIGHT! SO IF YOU WERE TO THROW IN SOME TOAST AND SOME JUICE, YOU’RE GOING TO BE MORE THAN READY TO START YOUR DAY OF SKIING. DARREN: NOW, WHEN WE SPEAK OF EFFICIENCY, WE MEAN THE ENERGY INPUT DIVIDED INTO THE USEFUL ENERGY OUT- PUT. WALNUTS HAVE AN ACCEPTED ENERGY INPUT OF ABOUT 28 KILOJOULES PER GRAM. BUT THE AVERAGE BODY USES 26.4 KILOJOULES PER GRAM. THAT MEANS WHEN IT COMES TO DIGESTING WAL- NUTS, THE AVERAGE BODY IS ABOUT 94% EFFICIENT. COLLEEN: SO WE CONVERT STORED CHEMICAL ENERGY OF FOOD INTO KINETIC ENERGY. SOME OF IT IS USEFUL BECAUSE IT HELPS US PERFORM USEFUL WORK. BRYCE: AND SOME OF IT’S WASTED OVERCOMING FRICTION, OR IT’S DISPERSED INTO SOUND WAVES OR THERMAL ENERGY. COLLEEN: AND SOME OF IT IS STORED FOR LATER USE. SARAH: WE USE EFFICIENCY CALCULATIONS TO COMPARE SIMILAR KINDS OF ENERGY CONVERSIONS. LET’S START WITH HYDROELECTRIC POWER. CAN YOU TELL ME HOW IT’S GEN- ERATED?

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