"Annenberg Media" "¶" "CAPTIONING IS MADE POSSIBLE BY THE ANNENBERG/CPB PROJECT" "SOMEWHERE BETWEEN SCIENCE AND FANTASY," "THERE'S A MURKY ZONE" "THAT'S ALWAYS BEEN THE MOST FERTILE GROUND" "FOR UNINHIBITED NEW IDEAS." "EVENTUALLY, THESE IDEAS FADE INTO HISTORY" "LIKE THE MUSIC OF THE SPHERES," "OR THEY BECOME OSSIFIED INTO SUPERSTITION" "LIKE ALCHEMY AND ASTROLOGY." "BUT FIRST THEY MAY HAUNT THE HUMAN IMAGINATION" "FOR CENTURIES." "THEY HAVE THEIR EFFECT ON SCIENCE AND SCIENTISTS." "I'D LIKE TO TELL YOU ABOUT ONE OF THOSE SHADOWY IDEAS." "ROGER BOSCOVICH..." "WAS BORN IN 1711," "THE SON OF AN ITALIAN MOTHER AND A YUGOSLAVIAN FATHER." "HE WAS TRAINED AS A JESUIT." "HE WAS AN ARCHITECT," "A DIPLOMAT, AN AUTHOR, AND MORE BESIDES." "HE WAS NOT A SCIENTIST," "BUT HE WAS WELL-READ IN THE SCIENCES." "HE HAD AN IDEA." "HE SAID, "SUPPOSE MATTER IS MADE UP OF ATOMS." ""THAT'S AN OLD IDEA." ""WHAT'S NEW IS WE NOW KNOW FROM ISAAC NEWTON" ""THAT WHEN THESE MASSES ARE FAR APART," "A FORCE ACTS BETWEEN THEM."" "HE DREW A DIAGRAM THAT LOOKED LIKE THIS." "HERE IS FORCE, HERE IS ZERO," "AND ON THIS AXIS, THE DISTANCE BETWEEN TWO ATOMS." ""WHEN THE TWO ATOMS ARE FAR APART," HE SAID," ""THE FORCE BETWEEN THEM IS ATTRACTIVE," ""THAT IS, LESS THAN ZERO." "AS THEY GET CLOSER TOGETHER, IT BECOMES BIGGER."" "IT GOES AS 1/r-SQUARED." ""BUT THAT'S TRUE ONLY WHEN THE TWO ATOMS" ""ARE VERY FAR APART." ""SUPPOSE WHEN THEY BECOME VERY CLOSE TOGETHER," ""THE FORCE TURNS AROUND" "AND BECOMES, INSTEAD OF ATTRACTIVE, REPULSIVE."" "IT GOES UP ABOVE ZERO ON THIS KIND OF DIAGRAM." "IT WOULD LOOK LIKE THAT." "WHEN THEY'RE CLOSER STILL," "IT MIGHT BECOME ATTRACTIVE AGAIN." "AND PERHAPS REPULSIVE AGAIN." "HE SAID, "IF THE FORCE LOOKS LIKE THIS," ""WHEN THE ATOMS ARE THIS FAR APART," "THERE'S NO FORCE BETWEEN THEM."" "THIS IS THE POINT WHERE THE FORCE IS ZERO," "AGAIN WHEN THEY'RE THIS FAR APART," "THERE'S NO FORCE BETWEEN ATOMS." "BUT THESE POSITIONS AREN'T EQUIVALENT." "ALTHOUGH THE FORCE IS ZERO HERE," "IF THE TWO ATOMS MOVE A LITTLE FURTHER APART," "THE FORCE BECOMES REPULSIVE AND TRIES TO PUSH THEM APART." "IF THE ATOMS MOVE CLOSER TOGETHER," "THE FORCE BECOMES ATTRACTIVE, NEGATIVE," "AND TRIES TO PULL THEM CLOSER TOGETHER." "ALTHOUGH THERE'S NO FORCE AT THIS POSITION," "THE POSITION ISN'T STABLE." "SUPPOSE THEY'RE IN THIS POSITION." "THEN THERE'S NO FORCE BETWEEN THEM." "IF THEY SHOULD MOVE CLOSER TOGETHER," "THE FORCE BETWEEN THEM BECOMES POSITIVE" "AND TRIES TO PUSH THEM BACK." "IF THEY SHOULD MOVE APART," "THE FORCE BECOMES ATTRACTIVE AND TRIES TO PULL THEM BACK." "THAT POSITION IS ONE OF STABLE EQUILIBRIUM." "THE IDEA IS THAT ATOMS CAN BE BOUND" "INTO STABLE WEBS OF MATTER" "MAKING UP THE WORLD THAT WE CAN SEE." "THIS IS NOT A LEGITIMATE SCIENTIFIC IDEA" "BECAUSE IT MAKES NO PREDICTION." "THERE'S NO WAY TO TEST IT." "YET IT'S AN EXTRAORDINARY IDEA" "MATTER IS MADE UP OF ATOMS BOUND BY FIELDS OF FORCE" "INTO POSITIONS OF STABLE EQUILIBRIUM." "THE LEGITIMATE SCIENTIFIC DISCOVERY OF ATOMS" "WAS MADE IN THE NEXT CENTURY BY JOHN DALTON." "THE LEGITIMATE SCIENTIFIC DISCOVERY" "OF FIELDS OF FORCE" "WAS MADE IN THE NEXT CENTURY BY MICHAEL FARADAY." "BUT BOTH OF THOSE MEN HAD BEEN IMPRESSED" "BY THIS STRANGE AND SHADOWY IDEA" "OF ROGER BOSCOVICH." "STABILITY." "THE STATE OF AN OBJECT" "THAT RETURNS TO ITS STARTING POINT" "WHEN IT'S DISTURBED." "LIKE A MARBLE IN A BOWL," "EVERY ATOM IN EVERY PIECE OF SOLID" "IN THE MECHANICAL UNIVERSE" "IS IN A POSITION OF STABLE EQUILIBRIUM," "NOT UNLIKE THE WEB OF MATTER IMAGINED BY ROGER BOSCOVICH." "BUT WHILE BOSCOVICH CONCEIVED OF STABILITY" "IN TERMS OF THE PLAY OF NEWTONIAN FORCES," "THE IDEA IS CLEARER IN THE CONCEPT OF ENERGY." "PERHAPS NOBODY APPRECIATES THE FLOW OF ENERGY MORE" "THAN A FIREFIGHTER," "PARTICULARLY WHEN THE HEAT'S ON." "HEAT IS ENERGY," "AND ENERGY IN ITS MANY FORMS" "IS ONE OF THE MORE DYNAMIC PROPERTIES OF THE UNIVERSE." "WHATEVER ITS FORM, NO MATTER ITS PURPOSE," "ENERGY IS EVERYWHERE." "IT ALWAYS WILL BE, AND IT ALWAYS WAS." "NO MATTER HOW IT'S USED OR ABUSED," "THE TOTAL AMOUNT OF ENERGY IN THE UNIVERSE" "NEVER DECREASES." "IN THE STOREHOUSE OF THE COSMOS," "THE SHELVES ARE AS AMPLY STOCKED TODAY" "AS THEY WERE THE MORNING" "THE UNIVERSE OPENED FOR BUSINESS." "THAT'S BECAUSE ENERGY IS CONSERVED," "WITHOUT EXCEPTION," "STRICTLY AND ABSOLUTELY." "ENERGY CANNOT BE CREATED," "NOR CAN IT BE DESTROYED." "BUT IT CAN BE CHANGED INTO DIFFERENT FORMS." "ENERGY CAN BE POTENTIAL," "AND ENERGY CAN BE KINETIC." "3,2 ,1 ,IGNITION." "ENERGY CAN BE ALMOST HEAVENLY," "AND IT CAN CAUSE SHEER HELL." "BUT NO MATTER WHERE OR HOW" "EVEN WHEN THE HEAT'S OFF" "ENERGY FLOWS FROM ONE THING TO ANOTHER," "EVEN FROM A SANDWICH TO A STUDENT FIREFIGHTER." "ENERGY FLOWS IN MANY WAYS, IN MANY FORMS," "AND TO AND FROM MANY THINGS." "ENERGY IS STORED IN MANY WAYS, FORMS, AND THINGS." "IT'S STORED IN THE FORM OF POTENTIAL ENERGY," "FOR INSTANCE, STORED IN A TANK OF GASOLINE" "WHICH IS LOADED WITH POTENTIAL ENERGY" "WAITING TO BE CONVERTED." "AND WHEREVER IT'S STORED," "POTENTIAL ENERGY DEPENDS ON POSITION" "NOT THE TANK'S POSITION," "BUT, IN THIS EXAMPLE, IN THE POSITIONS OF THE ATOMS" "WITHIN THE MOLECULES OF THE GASOLINE." "THE WAY ANY OBJECT STORES POTENTIAL ENERGY" "DEPENDS ON THE OBJECT'S POSITION." "THE HIGHER ABOVE THE EARTH ANY OBJECT IS," "THE MORE GRAVITATIONAL POTENTIAL ENERGY IT HAS." "THE POTENTIAL ENERGY CHANGES WITH THE OBJECT'S POSITION." "THE CLOSER AN OBJECT GETS TO THE GROUND," "THE LESS POTENTIAL ENERGY IT HAS." "OBVIOUSLY, THEN, POTENTIAL ENERGY" "IS RELATED TO POSITION." "WHILE POTENTIAL ENERGY RELATES TO POSITION..." "[FIRE ALARM RINGS]" "KINETIC ENERGY IS RELATED TO SPEED." "CLEARLY, A FAST-MOVING BODY HAS MORE KINETIC ENERGY" "THAN A SLOW-MOVING ONE." "[SIREN]" "HOWEVER, ANY BODY CAN TRADE POTENTIAL ENERGY" "FOR KINETIC ENERGY" "BY TRADING POSITION..." "FOR SPEED." "IN MUCH THE SAME WAY THAT AN OBJECT'S POTENTIAL ENERGY" "DEPENDS ON ITS POSITION NEAR THE EARTH," "AN ATOM'S POTENTIAL ENERGY DEPENDS ON ITS POSITION" "WITHIN THE MATTER IT'S BOUND TO." "MOLECULES WITHIN THE OIL HAVE PLENTY OF POTENTIAL ENERGY." "THEIR ATOMS ARE BOUND TOGETHER INTO MOLECULES" "BY THE ELECTRICAL FORCE BETWEEN ATOMS." "WHEN IGNITED, THEY BECOME REARRANGED" "INTO OTHER MOLECULES" "THAT CONTAIN LESS POTENTIAL ENERGY." "YOUNG FIREFIGHTERS WHO LEARN TO RESPECT THIS PHENOMENON" "HAVE THE POTENTIAL TO BECOME OLD FIREFIGHTERS." "REGARDLESS OF SPECIFIC AGE AND CIRCUMSTANCE," "A FIREFIGHTER'S ESSENTIAL RESPONSIBILITY" "IS TO PUT OUT THE FIRE." "THAT JOB OFTEN REQUIRES WATER" "FIRST, GETTING THE WATER," "AND THEN GETTING THE WATER FROM GROUND LEVEL TO THE FLAME." "TO DO THAT MEANS TO ENDOW THE WATER" "WITH POTENTIAL ENERGY." "ONCE AGAIN, THE UBIQUITOUS FLOW OF ENERGY CAN BE SEEN," "EVEN IN THE FLOW OF WATER." "THERE'S WORK TO BE DONE HERE." "THAT WORK, PROVIDED BY THE WATER PRESSURE'S FORCE," "AT FIRST TURNS INTO THE KINETIC ENERGY OF THE WATER" "LEAVING THE NOZZLE AT HIGH SPEED." "AS THE WATER RISES AGAINST THE FORCE OF GRAVITY," "SOME KINETIC ENERGY BECOMES POTENTIAL ENERGY." "MORE WATER!" "WITH A GOOD CREW AND ENOUGH PRESSURE BEHIND IT," "THE WATER CAN SOAR TO ITS DESTINATION." "ONE WAY OR ANOTHER," "HUMANS HAVE ALWAYS WANTED TO SOAR HIGHER AND HIGHER." "IN THIS CENTURY," "SEVERAL ROSE AS HIGH AS 400,000 KILOMETERS." "AND IN THE LAST CENTURY," "THE PULL UPWARD WAS JUST AS STRONG," "AT LEAST IN THE FAR-REACHING IMAGINATION OF JULES VERNE." "THE LUNAR JOURNEY HE IMAGINED" "WAS TAKEN ON THE WINGS OF A CANNONBALL ROCKET." "FAR-FETCHED?" "PERHAPS." "BUT ACCORDING TO JULES VERNE," "TO REACH THE MOON, ALL SPACE TRAVELERS NEEDED" "WAS ENOUGH KINETIC ENERGY TO BEGIN WITH." "BEYOND THE REALM OF SCIENCE FICTION," "THE MOON'S GRAVITY CAN INDEED HELP A PROJECTILE" "FINISH ITS JOURNEY." "AS FAR AS IT GOES, THAT MUCH IS TRUE." "BUT COULD A VESSEL REALLY ESCAPE FROM THE EARTH" "WITHOUT AN ENGINE OF ITS OWN?" "THE IDEA HAS A LOT OF POTENTIAL," "BUT GETTING THERE WILL TAKE SOME WORK." "THE WORK REQUIRED TO LIFT AN OBJECT" "AWAY FROM THE EARTH'S SURFACE" "IS GIVEN BY THE FORCE OF GRAVITY" "INTEGRATED OVER THE DISTANCE." "THE WORK IS THE CHANGE IN POTENTIAL ENERGY." "IF THE VESSEL" "IS LIFTED TO INFINITY," "IT HAS A POTENTIAL ENERGY" "OF ZERO." "SO ON THE EARTH'S SURFACE" "ITS POTENTIAL ENERGY" "IS NEGATIVE." "TO ESCAPE THE EARTH," "IT MUST BE GIVEN" "SOME KINETIC ENERGY," "ENOUGH SO THAT IT WON'T SLOW DOWN TO ZERO" "BEFORE IT GETS INFINITELY FAR AWAY." "THE TOTAL ENERGY IS ZERO," "BOTH AT INFINITY" "AND ON THE SURFACE." "THE VESSEL WILL ESCAPE IF IT STARTS WITH A SPEED" "OF ABOUT 11 KILOMETERS PER SECOND." "WHILE ASTRONAUTS ZOOM UPWARD WITH ROCKETS," "FIREFIGHTERS TEND TO HEAD TOWARD THEIR DESTINATION UPWARD" "UNDER THEIR OWN POWER." "SAFETY PRECAUTIONS USUALLY CLOSE THE DOOR ON THE ELEVATOR." "WHEN A FORKLIFT ISN'T HANDY, THAT LEAVES THE FEET." "FIREFIGHTERS NEED MORE THAN SURE FOOTING" "TO CLIMB LADDERS." "THEY NEED ENERGY." "THE ENERGY SOURCE IS THE FOOD THEY EAT." "TO ANYONE WHO NEEDS A CERTAIN AMOUNT OF ENERGY" "TO FINISH THE JOB," "THE FACT THAT HUMAN ENERGY COMES FROM FOOD" "MAY BE NO SURPRISE." "THIS FACT, HOWEVER, MAY COME AS A SURPRISE" "THE AMOUNT OF FOOD IT TAKES TO GET THE JOB DONE" "CAN BE CALCULATED." "CONSIDER, FOR EXAMPLE, THIS FIREFIGHTER'S TASK" "AND THE FACTORS INVOLVED." "THE POTENTIAL ENERGY NEEDED HAS TO EQUAL mgh." "THAT'S HIS MASS TIMES THE ACCELERATION OF GRAVITY" "TIMES THE HEIGHT HE REACHES." "AN AVERAGE FIREFIGHTER WEARING GEAR" "WEIGHS 90 KILOGRAMS." "THE ACCELERATION OF GRAVITY" "IS ABOUT 10 METERS PER SECOND SQUARED." "A 10-STORY BUILDING" "IS ABOUT 30 METERS HIGH." "THEREFORE, THE FIREFIGHTER'S" "FINAL POTENTIAL ENERGY" "IF HE WERE TO GO AS HIGH AS 10 FLOORS UP" "WILL BE 90 TIMES 10 TIMES 30," "OR 27,000 KILOGRAM METERS SQUARED" "PER SECOND SQUARED," "ALSO KNOWN AS JOULES" "AND NAMED AFTER JAMES PRESCOTT JOULE." "JOULE DEMONSTRATED THAT ABOUT 4.2 JOULES" "ARE EQUIVALENT TO 1 CALORIE OF HEAT." "SO THE FIREFIGHTER'S POTENTIAL ENERGY, mgh," "AMOUNTS TO A LITTLE OVER 6,000 CALORIES." "BUT A FOOD CALORIE," "THE KIND DIET BOOKS GO ON AND ON ABOUT" "WITH A CAPITAL "C,"" "IS ACTUALLY 1,000 HEAT CALORIES." "THE NET RESULT OF THIS FIREFIGHTER'S EFFORTS," "IF HE WERE TO CLIMB TO THE TOP OF A 10-STORY BUILDING," "WOULD BE TO TURN ABOUT 6 FOOD CALORIES" "FROM HIS ENERGY RESERVES" "INTO POTENTIAL ENERGY." "THAT'S THE TINY FRACTION TRANSFERRED" "TO THE POTENTIAL ENERGY OF HIS BODY 30 METERS ABOVE THE GROUND." "FOR TURNING FOOD ENERGY INTO MECHANICAL ENERGY," "THE HUMAN BODY IS AN AMAZINGLY INEFFICIENT MACHINE." "MOSTLY, THAT MACHINE USES ENERGY" "JUST TO KEEP ITSELF GOING," "BREATHING, DIGESTING, METABOLIZING," "AND MERELY STAYING ALIVE." "BUT SOMETIMES THAT TINY FRACTION" "SEEMS TO COUNT FOR EVERYTHING." "THAT TINY BIT BECOMES MUSCULAR FORCE TIMES HEIGHT." "THAT CRUMB OF FOOD ENERGY TURNS INTO WORK," "AND WORK ITSELF IS THE TRANSFER OF ENERGY" "FROM ONE FORM TO ANOTHER." "FOR EXAMPLE, A SPRINTER WORKS AGAINST HIS OWN INERTIA" "AND TURNS FOOD ENERGY INTO KINETIC ENERGY." "A POLE-VAULTER ALSO STARTS" "BY DOING THE WORK TO GET HIMSELF MOVING," "BUT IN TERMS OF ENERGY, HE TAKES THINGS FARTHER." "THE VAULTER TURNS HIS KINETIC ENERGY" "INTO POTENTIAL ENERGY" "WHICH IS STORED IN THE POLE." "THAT, IN TURN, BECOMES THE POTENTIAL ENERGY" "OF HIS OWN BODY SOARING OVER THE BAR." "AT THIS POINT, HIS POTENTIAL ENERGY" "TURNS BACK INTO KINETIC ENERGY," "WHICH IS FINALLY DISSIPATED INTO USELESS HEAT." "HUMANS CONSTANTLY TURN FOOD ENERGY" "INTO OTHER ENERGY FORMS." "EVEN WHEN AN ATHLETE WORKS HER BODY TO THE UTMOST," "SHE TURNS ONLY A FRACTION OF HER FOOD ENERGY" "INTO THE KINETIC OR POTENTIAL VARIETY." "YET NO MATTER THE AMOUNT USED," "BODIES IN MOTION ILLUSTRATE THE IDEA OF ENERGY." "NO MATTER THE ACTIVITY, PROPELLING THE BODY IS WORK." "WORK IS A FORCE, HERE A MUSCULAR FORCE," "APPLIED THROUGH A DISTANCE." "WORK SHIFTS ENERGY FROM ONE SYSTEM TO ANOTHER," "FOR EXAMPLE, FROM THE INTERIOR OF THE BODY" "TO A MORE SIMPLE AND VISIBLE FORM," "LIKE THE KINETIC AND POTENTIAL ENERGY" "OF A DISCUS IN FLIGHT" "OR THE POTENTIAL ENERGY OF SOMEONE CLIMBING A LADDER." "OF COURSE, CLIMBING A LADDER REQUIRES BALANCE." "SO DOES WASHING WINDOWS." "IN THE PHYSICAL REALM," "WHEN ALL THE FORCES ARE BALANCED," "EQUILIBRIUM EXISTS." "BUT MERE EQUILIBRIUM DOESN'T INSURE SAFETY." "SAFETY" "NO CHANCE ROLLING, SLIDING, STUMBLING," "OR OTHERWISE COMING TO HARM" "REQUIRES A SPECIAL KIND OF EQUILIBRIUM." "IT'S CALLED STABLE EQUILIBRIUM." "STABLE EQUILIBRIUM CAN ALWAYS BESEENON AGRAPH" "OFPOTENTIALENERGY VERSUSPOSITION." "THEFORCEON ABODY TENDSTOPUSHIT" "TOWARDPOSITIONS OF LOWER POTENTIAL ENERGY." "THESTEEPERTHESLOPE," "THEBIGGER THEFORCETHATRESULTS." "INFACT,THEFORCE" "ISJUSTEQUAL" "TO MINUS THE RATE OF CHANGE" "OFPOTENTIALENERGY." "SINCE IT DEPENDS ON THE SLOPE" "OFTHEPOTENTIALENERGY," "NOTITSSIZE," "POTENTIALENERGY" "CAN BE POSITIVE OR NEGATIVE" "WITHOUT CHANGING ITS EFFECT." "WHENTHESLOPEISZERO ," "THERE'S NO FORCE ON THE BODY." "ITISIN EQUILIBRIUM." "THAT EQUILIBRIUM MAY BE STABLE," "LIKE BEING SECURELY NESTLED" "IN A VALLEY," "OR IT CAN BE UNSTABLE," "LIKE BEING PRECARIOUSLY" "PERCHED ON A PEAK." "SEEN IN TERMS OF FORCE," "THIS IS EXACTLY THE PICTURE" "ROGER BOSCOVICH HAD IN MIND." "FOR EXAMPLE, THE POTENTIAL ENERGY" "OF A PAIR OF HYDROGEN ATOMS" "HAS A POSITION OF STABLE EQUILIBRIUM." "THE POTENTIAL ENERGIES OF INTERACTIONS BETWEEN ATOMS" "ARE DUE TO THE ELECTRICAL FORCES BETWEEN THEM," "CAUSG ATTRACTION WHEN THEY'RE FAR APART." "AT SMALLER DISTANCES," "THEY RESIST BEING SQUEEZED TOGETHER." "THE RESULT IS AN EQUILIBRIUM POSITION" "WHERE ATTRACTION AND REPULSION ARE IN PERFECT BALANCE." "AT THAT POSITION, THEY BIND INTO A HYDROGEN MOLECULE." "BALANCED ON THE RUNGS OF THE FIREFIGHTER'S LADDER," "POTENTIAL ENERGY DEPENDS ON POSITION." "POTENTIAL ENERGY IS REDUCED" "BY MOVING TO A LOCATION NEARER THE GROUND." "THE PLACE WHERE POTENTIAL ENERGY IS LOWEST," "WHERE SOMETHING CAN FALL NO FARTHER," "IS THE ONLY PLACE WHERE STABILITY NO LONGER MATTERS." "WHEN AN OBJECT STARTS FROM AND RETURNS TO" "THE SAME ELEVATION," "THERE'S A NET POTENTIAL ENERGY CHANGE OF ZERO." "THEREFORE, FROM A PHYSICS POINT OF VIEW," "DESPITE ALL THIS HEALTHY ACTIVITY," "NO NET WORK HAS BEEN ACCOMPLISHED." "AT THE SAME TIME, BECAUSE OF ALL THIS HEALTHY ACTIVITY," "IT LOOKS LIKE A LOT OF WORK GETS DONE." "THE CURIOUS PART, FROM AN HISTORICAL PERSPECTIVE," "IS THAT THESE BODIES VOLUNTEER TO DO IT." "IN THE BAD OLD DAYS," "MACHINES WERE LIKEWISE USED TO TRANSMIT AND AMPLIFY FORCES," "BUT THE SUBJECTS WERE HARDLY VOLUNTARY." "UNLIKE THE MACHINES OF TODAY," "WHICH EXTEND THE BODY'S ENDURANCE," "THESE MACHINES EXTENDED THE BODY ITSELF." "OFTEN, THE MERE SIGHT OF SUCH MACHINES" "WOULD INFLUENCE THE WRONGDOER" "TO CONFESS ALL MANNER OF TRANGRESSIONS," "REAL OR IMAGINED." "THIS PRACTICE, WHICH WAS USED VERY EFFECTIVELY" "ON COUNTLESS TERRIFIED PRISONERS," "WAS CALLED SHOWING THE INSTRUMENTS." "WE'VE NOW REACHED A CRITICAL JUNCTURE IN THIS COURSE." "WE'VE LEARNED ABOUT FORCE, ACCELERATION, ENERGY, WORK," "IN FACT, ALL THE TOOLS YOU NEED TO SOLVE PROBLEMS IN MECHANICS." "WHAT KIND OF PROBLEMS ARE YOU PREPARED TO SOLVE?" "HERE'S A GOOD EXAMPLE." "HERE'S AN INCLINED PLANE." "ON THE PLANE, THERE'S A CART WITH SOME MASS." "THE MASS APPLIES A FORCE STRAIGHT DOWN." "THERE'S A STRING ATTACHED TO IT" "WHICH RUNS UP OVER A PULLEY AND COMES DOWN." "THERE'S ANOTHER MASS HANGING FROM THAT" "APPLYING A FORCE DOWN THIS DIRECTION." "THERE'S SOME COEFFICIENT OF FRICTION AT THIS POINT" "BETWEEN THE CART AND THE PLANE." "THE PLANE IS INCLINED AT SOME DEFINITE ANGLE, THETA." "HOW BIG MUST THIS MASS BE" "TO MAKE THE CART BARELY START MOVING?" "YOU KNOW EVERYTHING YOU NEED TO KNOW" "TO SOLVE THAT PROBLEM." "YOU MIGHT REASONABLY ASK," "HOW WILL WORLD CULTURE BE ADVANCED" "IF YOU MANAGE TO FIND THE SOLUTION TO THAT PROBLEM?" "THE ANSWER IS, IT WON'T BE." "BUT YOU'D HAVE A CHANCE" "TO TRY OUT THE TOOLS YOU'VE LEARNED," "AND I'D HAVE SOME PEACE AND QUIET" "WHILE YOU SOLVE THE PROBLEM." "ABOVE ALL, IT'S TRADITIONAL." "GENERATIONS OF STUDENTS HAVE HAD TO STRUGGLE" "THROUGH PROBLEMS ON INCLINED PLANES AND PULLEYS." "WE KNOW FROM 17th-CENTURY LETTERS" "THAT EVEN THEN STUDENTS CONSIDERED MECHANICS A DULL SUBJECT." "OUR JOB IS TO GET YOU EXCITED ABOUT LEARNING SCIENCE," "AND WE'VE REACHED THE POINT" "WHERE IT'S TRADITIONAL TO GRIND YOU DOWN WITH PROBLEMS." "WHAT DO WE DO?" "THE COMMITTEES THAT GOVERN WHAT WE DO IN THIS COURSE" "HAVE DEBATED AND DELIBERATED ON THAT PROBLEM," "AND THEY'VE FINALLY COME TO A DECISION." "THEY'VE AUTHORIZED ME TO SHOW YOU THE INSTRUMENTS." "I'LL SEE YOU NEXT TIME." "CAPTIONING PERFORMED BY THE NATIONAL CAPTIONING INSTITUTE, INC." "CAPTIONS COPYRIGHT 1985 CALIFORNIA INSTITUTE OF TECHNOLOGY," "THE CORPORATION FOR COMMUNITY COLLEGE TELEVISION, AND THE ANNENBERG/CPB PROJECT" "Annenberg Media" "¶" "For information about this and other Annenberg Media programs call 1-800-LEARNER and visit us at"