energy scientific method teachers guide discovery education

8/8/2019 Energy Scientific Method Teachers Guide Discovery Education

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

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Team Leader: Bob Holzer

Writer: John Watson

Editor: CHAOS Communications

Producer: Michele Boniface

Con tent Revi ewers : Donna Ma tovi novic

Stella Shru m

Produ ced by ACCESS The Education Station

1997 Alberta Education

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506).

MCMXCVII Alberta Education


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CONSERVATION LAWS

Teachers Gu ide

Table of Contents

Introduction ............................................................1

Program Summary ................................................1

Links to Cur riculum Standard s ...........................1

Pre-Test ....................................................................3

Teacher Preparation/ Instructional Notes ..........3

Stud ent Objectives .................................................3

Stud ent Preparation ...............................................4

Blackline Masters ...................................................4

Answer Key ............................................................5

Script of Video Narration .....................................9

This video is closed captioned

The pur chase of this video program entitles the user to the

right to reprod uce or du pl icate, in w hole or in part , this

teacher's guide and the blackline master han dou ts that accom-

pan y it for the pu rpose of teaching in conjunction w ith this

video, Conservation Laws. This right is restricted on ly for use

with this video program . Any reprodu ction or du plication in

wh ole or in part of this guide and the blackline master hand -

outs for any purp ose other than for use with this video pro-

gram is p rohibited.


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The total energy of the universe is constant. Energy can

be transferred by collisions in chemical and nu clear reac-

tions, by light waves and other rad iations, and in m any

other ways. However, it can never be destroyed . As these

transfers occur, the matter involved becomes stead ily less

ordered.

All energy can be considered to be either kinetic energy,

which is energy of motion; potential energy, which depends

on relative position; or energy contained by a field, such as

electromagnetic waves.

Everything tend s to become less organized and less or-

der ly over time. Thus, in all energy tran sfers, the overall

effect is that the energy is spread ou t un iformly. Examplesare the transfer of energy from h otter to cooler objects by

cond uction, rad iation, or convection and the w arming of

our surround ings wh en we burn fuels.

Life Science: Matter, energy, and organization in living sys-

tems

As matter and energy flows through different levels of

organization of living systems cells, organs, organisms,

comm un ities and betw een living systems and th e physi-

cal environm ent, chemical elements are recombined in d if-

ferent ways. Each recombination results in storage and

dissipation of energy into the environm ent as heat. Matterand energy are conserved in each change.

Earth and Space Science: Geochemical cycles

Movement of matter between reservoirs is driven by the

earth's internal and external sources of energy. These move-

ments are often accomp anied by a change in the p hysical

and chemical properties of the matter. Carbon, for example,

occurs in carbonate rocks such as limestone, in the atm o-

sphere as carbon d ioxide gas, in water as dissolved carbon

dioxide, and in a ll organisms as comp lex molecules that

control the chemistry of life.


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PRE-TEST

A Pre-Test is includ ed with the Blackline Masters for thisprogram . It is meant to be ad ministered before the video

and its ensuing activities are used . This assessment tool

allows you to gauge stud ent comprehension of the Objec-

tives before completing the lesson; its results may be con-

trasted with those of the Post-Test, also includ ed herein, to

assess compr ehension of the Objectives after completing

the lesson.

TEACHER PREPARATION/INSTRUCTIONAL NOTES

Before presenting this lesson to your stu den ts we su ggestthat you p review the video and review th is guide, and the

accomp anying blackline master activities in ord er to famil-

iarize yourself with their content.

As you review the materials presented in this guide, you

may find it necessary to make some changes, additions, or

deletions to meet the specific needs of your class. We en-

courage you to do so, for only by tailoring th is program to

your class will they obtain the maximum instru ctional ben-

efits afforded by th e materials.

It is also suggested th at the video p resentation take place

before the entire group u nd er your sup ervision. The les-

son activities grow out of the context of the video, there-

fore, the p resentation should be a common experience for

all stud ents.

STUDENT OBJECTIVES

After viewing the video and participating in the follow-up

activities, students w ill be able to:

Identify evidence for the conservation of mass. Apply the first and second laws of thermodynamics.

Define and calculate kinetic energy.


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Define and calculate gravitational potential energy.

Identify various forms of energy. Appreciate that chemical, physical and biological

systems are all subject to the same basic laws.

STUDENT PREPARATION

This video is one of a series. Before students view th is pro-

gram an d comp lete the follow-up activities, they should

be able to:

1. Explain the meaning of the phrase, Matter is conservedin a closed system .

In a system in which matter cannot enter or leave, the total mass,and therefore the total number of atoms, does not change.

2. Write a balanced chemical equation for the photosyn-thesis reaction.

6CO2(g)

+ 6H2O

(l)+ energy C

6H

12O

6(s)+ 6H

2O

(g)

3. Use coefficients to balance the following chemical reac-tion equ ation: Al

(s)+ Br

2(l) AlBr

3(s)

2Al(s)

+ 3Br2(l)

2AlBr3(s)

4. Identify the units used to measure energy and w ork.

The unit of energy and work is the joule.

If stud ents have d ifficulty with any of the items, you shou ldreview the concepts in reference materials before viewing

the video.

BLACKLINE MASTERS

The following blackline m aster activity sheets are included

with this guide. Dup licate and distribute those you wish to

use. An Answer Key app ears on pages 5-8.

(1.) Blacklin e M aster # 1: Pre-Test is to be given to you r

stud ents prior to viewing the video to assess their p riorknow ledge of the topic. It may be contrasted to Blackline

Mas ter # 9: Post-Test to gauge student comp rehension of

the Objectives after the lesson has been completed.


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(2.) Blacklin e Master #2: Glossaryis a list of terms fromthe video. Stud ents may find this hand out helpful wh en

completing the activities w hich accomp any this lesson, as

well as for preparation for the Post-Test.

(3.) Blackl ine Master #3: A Valian t Effort asks students

to identify various factors in van Helmonts experiment.

(4.) Blacklin e Master #4: Smok e and M atters explores

the p rocess of comp osting.

(5.) Blackli ne Mast ers #5a-5b: Energy on the Move as-

signs a mathematical equation to the calculation of kinetic

energy.

(6.) Blacklin e Masters #6a-6b: Potential Energy exploresthe formula used to calculate gravitational potential energy.

(7.) Blacklin e M aster #7: A Joule of an Idea examines

James Prescott Joules experiments with work.

(8.) Blackline Master #8: Energy investigates useful an d

waste energy.

(9.) Blackline Masters #9a-9d: Post-Test is an assessmenttool to be used after the v ideo and follow-up activities havebeen completed. The test is based d irectly on the Studen tObjectives for this program and the National Science Edu-cation Stand ard s for grades 9-12.

ANSWER KEY

Blacklin e M aster #1: Pre-Test

1.F

2.T

3.T

4.F

5.F

6.T

7.T8.T

9.F

10.F


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Blacklin e Masters #3-8

Note that some of these questions have more than onepossible answer.

1. Manipula ted var iable: t imeResponding variable: change in mass Controlledvariables: nutrients received

2. To imp rove the experimental design requires monitor-ing the atmosphere around the plant.

3. Newton meant his accomplishments were madepossible, in p art, because of the work others had don ebefore him.

4. a. This is a prediction.

b. The energy is released as a result ofthe cellular respiration by the d ecay of organisms.

c. manipu lated variable: contents of the container;respond ing variable: temp erature;controlled variables: time, environmental

conditions

5. Two flasks containing identical clipp ings would besubjected to identical cond itions except air circulationshould be stopped in one and not the other.

6. Ek

= 13 J

7. m = 54 kg

8. Ek

= mv2

2Ek

= m v2

v2 =

v =

9. v = 29.6 m/ s

10. The billiard ball has greater potential energy becauseit has greater mass.

11. Ep

= 6.7 J (remem ber to convert gram s to kilograms!)

1

2

2Ek

m

mu ltiply by 2

divide by m

take the square root2Ekm


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12. Ep

= mgh divide both sides by gh

m =

13. Ep

= 4.1 105 J (or 0.41 MJ)

14. Ep

= mgh

m =

m =

m = 75 kg

15. a. Kinetic energy of the moving arm becomes kineticenergy of the sand . Friction between the sandgrains results in an increase of therm al energy in thesand.(The kinetic energy was originally chem ical potentialenergy in the bod y tissues.)

b. No, careful measurements of the inpu t and outpu tenergy would be required.

16. m = 0.5(5.0 L)(1 kg) = 2.5 kg = 2.5 103 gQ = mct

= (2.5 103 4)(4.19 J/ 47)(637)= 6.6 105 J or 0.66 MJ

17. The second law of thermod ynam ics says that heatalways flows from a hotter to a cooler object. Duringdiffusion, matter m oves from a higher to a lowerconcentration. So the two are very similar. They aredifferent, however, in that heat is not a su bstance, andonly matter can d iffuse.

Blackline Masters #9a-9d: Post-Test

Multiple Choice

1. b. dependen t var iable2. c. Antoine Lavoisier3. d . all of th e above

Ep

gh

4.8 105 kg m2

s2

(9.81 ) (650 m)m

s2

Epgh


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Long Answ er

1. That the tree interacts with the atmosphere as well asthe soil.

2. 2 HgO(s)

+ energy > 2Hg(l)

+ O2(g)

2Mg(s)

+ O2(g)

> 2 MgO(s)

3. In a chemical reaction mass is conserved.4. carbon dioxide is released throu gh stomata

carbon dioxide is released w hen the tree burnscarbon is returned to the biosphere w hen the tree de-composes

5.Ek = 1/ 2mv 2

6.Ek = 1/ 2mv 2

= 1/ 2(57.2 kg)(4.00 m/ s)2

Ek =458 J

7. gravitational potential energy of the ball is converted tokinetic energy8.Ep = mgh

= (20.5 kg)(9.81 m/ s2)(2.00 m)Ep = 402 J

9. a. A remote controlled car power by a 9.0 volt bat-tery; chem ical poten tial energy of the battery in, kineticenergy of the car ou tb. A cyclist coasting d ownhill; gravitational potentialenergy in, kinetic energy outc. A log burning; chemical potential energy of the login, thermal energy, light ou t

10. sugar cane; corn (wheat and other grains)

11. Ep = mghh =Ep / mg

= (7.36 J) / (0.500 kg)(9.81 m/ s2)h = 1.50 m

12. They are both captured and converted solar en-ergy.

13. conservation of energy ; energy can be trans-formed from one form to another bu t it cannot bedestroyed

14. heat; He measured the amount of work doneturn ing a padd le wheel in a closed container full ofwater. He compared the initial and final temperature ofthe water to determine the amount of thermal energygained.

15. flows always flows from matter at a higher tem-peratu re to matter at a lower temperature; useful en-ergy diminishes with every energy conversion

16. temperatu re d ifference


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SCRIPT OF NARRATION

DAN A: ACTION. REACTION. MOTION. OVER THE YEARS, MAN Y

PEOPLE H AVE TRIED TO DESIGN A SYSTEM THAT WOULD RUN

FOREVER A SYSTEM YOU CO ULD SET IN MO TION THA T

WOULD NEVER NEED ANY MORE ENERGY ADDED SOME-

THING CALLED A PERPETUAL MOTION MACHINE. NO ON ES

COME UP WITH ON E YET. WH Y IS THAT? THE ANSWER IS SIM-

PLY SCIENCE. SCIENTISTS USE EXPERIMENTS TO TRY TO FIGURE

OUT H OW TH E WORLD WORKS. THEY ASK THE QUESTION

WH AT IF? AND TH EN THEY RECORD THEIR OBSERVATIONS.

FINALLY, THEY SUGGEST A THEORY TO EXPLAIN WHAT THEY

H AVE OBSERVED. IF ENO UGH EXPERIMENTS SUPPORT THE

CONCEPT OF A THEORY, SCIENTISTS CALL IT A LAW. SCIENCE

IS ABOUT TRIAL AND ERROR. DESPITE THEIR MAN Y ACH IEVE-

MEN TS, EVEN SOME OF TH E GREATEST MIND S IN SCIEN CE

H AVE BEEN FRUSTRATED BY THEIR ATTEMPTS TO UN LOCK

NATURES SECRETS.

JENN IFER: IN THE 1600S, A BELGIAN DOCTOR NAMED JAN VAN

HELMONT WONDERED WHERE PLANT MATTER CAME FROM.

JOH N: HE USED A FURNACE TO DRY ABOUT 91 KILOGRAMS OF

SOIL. THEN HE PLANTED A TREE WITH A MASS OF ABOUT 2.25

KILOGRAMS IN THE SOIL.

JENNIFER: FOR ABOUT FIVE YEARS VAN H ELMON T KEPT THE

SOIL IN TH E POT COVERED SO THAT NO DUST WOULD ENTER.

THE ON LY THING HE ADDED WAS DISTILLED WATER.

JOH N: WH ICH M EAN S ITS NOT REALLY A CLOSED SYSTEM,

BECAUSE ITS RECEIVING MATTER OR WATER FROM THE

OUTSIDE. AT THE END OF FIVE YEARS, VAN HELMONT DUG UP

THE TREE AND WEIGHED IT. HE DISCOVERED THE SOIL HA D

LOST 0.275 KILOGRAMS, BUT THE TREE HAD GAIN ED 75 KILO-

GRAMS.

JEN N IFER: OBVIOUSLY TH E INCREASE IN TH E TREES MASS

DIDNT COME FROM THE SOIL. SO WH ERE DID IT COME FROM?

JOHN : VAN HELMONT THOUGHT HE HAD CON TROLLED ALLTHE MATTER ENTERING AN OTHERWISE CLOSED SYSTEM. SO

HE CONCLUDED THE 75 KILOGRAMS OF WOOD, BARK, AND

LEAVES WERE FORMED ENTIRELY FROM THE WATER.


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BRENDON: HOW DO PLANTS CON VERT CARBON DIOXIDE INTO

FOOD?

MIKE APPS: THROU GH TH E PROCESS OF PHO TOSYN THESIS.

SOLAR ENERGY H ELPS THE CH LOROPH YLL MOLECULES TO

CHA NGE CARBON DIOXIDE INTO SUGARS AND O THER CAR-

BOHYDRATES IN THE LEAVES.

BRENDON : I KNOW THAT VAN HELMON T TRIED TO ISOLATE A

SYSTEM COMP LETELY. I GUESS H E DIDN T TAKE INTO AC-

COUN T PHO TOSYNTH ESIS.

MIKE APPS: IN FACT, IF YOU MEASURE THE MASS OF A TREE,

AND YOU BREAK IT DOWN INTO ITS VARIOUS PARTS, YOULL

FIND TH AT THE TREE HAS ABOUT 50% OF ITS MASS IN WATER.

AND ALL OF THAT CAME FROM THE ROOTS. THE REMAININ G

50% HALF OF IT IS, IN FACT, CARBON . AN D ALL OF THAT

CAME FROM THE LEAVES THROU GH PH OTOSYN THESIS. SO

ABOUT 25% OF THE MASS OF A TREE, ROUGHLY, IS CARBON

THATS BEEN REMOVED FROM TH E ATMOSPH ERE.

DAN A: SO THE ANSWER, IN PART AT LEAST, IS THAT PLAN T

MATTER COMES FROM CARBON DIOXIDE IN THE AIR. VAN

HELMONT NEVER EVEN CONSIDERED THE POSSIBILITY THAT

AIR COULD TAKE PLACE IN A CH EMICAL REACTION. IT WASNT

REALLY VAN HELMON TS FAULT. SCIENCE IN THE 1600S JUST

DIDNT HAVE THE KNOWLEDGE BASE TO ANSWER THE QUES-

TION HE ASKED. VAN HELMONTS EXPERIMENTAL DESIGN WAS

SOLID. HIS SYSTEM JUST WASNT AS CLOSED AS HE THOUGH T.

TARA: WHEN A LOG BURNS, WE END UP WITH A PILE OF ASHES.

SO WH ERE DOES EVERYTHIN G GO? IT DIDN T SEEM TO MAKE

THAT MUCH SMOKE.

DAN A: HO W WOULD YOU DESCRIBE TH E CHEMICAL REAC-

TION WE CALL PH OTOSYNTH ESIS?

JENN IFER: WELL, CARBON DIOXIDE AN D WATER COMBINED

WITH ENERGY GIVES US OXYGEN AND GLUCOSE.

DAN A: GOOD. NO W, HOW ABOUT USING SYMBOLS, JOH N.

JOH N: WEVE GOT IT HERE:

DAN A: RIGHT. BUT WHEN W E USE SYMBOLS, WE HAVE TOMAKE SURE WE BALANCE THE EQUATION.

JOH N: SO WE GET:

DANA: GOOD. NOW LOOK AT THIS. WH AT ATOMS DO WE HAVE


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IN TH E REACTANTS?

JENNIFER: WELL, THERE ARE 6 CARBON H ERE. AN D FOR OXY-

GEN WE H AVE 6 TIMES 2 IS 12, AN D 6 MO RE IS 18.

JOH N: AN D 6 TIMES 2 IS 12 HYDROGEN.

DAN A: RIGHT.\ E AND BECAUSE WE BALANCED THE EQUA-

TION, WE KNOW THAT TH E ATOMS PRESENT IN THE REAC-

TANTS ARE PRESENT IN THE PRODUCTS.

JOHN: THATS IMPORTANT.

DAN A: WELL, IT SEEMS THAT IN A CHEMICAL REACTION AT-

OMS ARE NEVER CREATED OR DESTROYED.

JENNIFER: TH EY JUST CHAN GE PLACES.

DAN A: AN D WH ERE DOES TH E MASS OF AN OBJECT COME

FROM?

JENNIFER: THE ATOMS.

JOHN: SO IN A CHEMICAL REACTION, MASS IS NEVER CREATED

OR DESTROYED EITHER.

SCOTT: IN 1774, AN TOINE LAVOISIER PERFORMED AN EXPERI-

MENT IN A CLOSED SYSTEM SO THAT N O MATTER COULD EN-

TER OR LEAVE ONCE THE

REACTION HAD BEGUN. LAVOISIER USED MERCURY (II) OX-

IDE. BUT MERCURY IS A TOXIC SUBSTAN CE, SO ITS SAFER TO

USE MAGNESIUM. JUST LIKE LAVOISIER, WE CAREFULLY MEA-

SURE THE MASS OF THE REACTAN T, PLACE IT IN A CLOSED SYS-

TEM AN D IGNITE IT. THIS CREATES AN EXOTH ERMIC REAC-

TION: WH EN WE MEASURE THE MASS OF THE PRODUCTS, WE

DISCOVER THE TOTAL MASS OF THE PRODUCTS IS IDENTICAL

TO TH E TOTAL MASS OF TH E REACTANTS. LAVOISIER CON -

CLUDED THAT ALTHOUGH ATOMS HAD REARRANGED THEM-

SELVES, THEY WERE ALL ACCOU N TED FOR. RESTATED,

LAVOISIERS CONCLUSIONS BECAME KNOWN AS THE LAW OF

CON SERVATION OF MASS.

BRENDON : WE TALKED ABOUT PH OTOSYNTHESIS AFFECTING

THE AMOUN T OF CARBON. NOW, HOW WOULD A FIRE AFFECT

THE AMOUN T OF CARBON ?

MIKE APPS: THATS A GOOD Q UESTION , BECAUSE WE OFTENFORGET ABOUT FIRE. BUT FIRE IS ANO THER WAY BY WH ICH

THE CARBON THATS BEEN FIXED IN THE TREE, THROUGH PHO-

TOSYNTH ESIS, ENDS UP GOIN G BACK TO THE ATMOSPHERE. A


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FIRE GOES THROUGH AN D IT BURNS PART OF THE TREE, AND

THE CO MBUSTION PRODU CTS TH ATS CARBON DIOXIDE,

CARBON MONOXIDE, AND JUST A LITTLE BIT OF METHANE

GO BACK UP INTO THE ATMOSPHERE. BUT THE EFFECT OF THE

FIRE IS NO T PRIMARILY THAT CO MBUSTION . IT DOESNT RE-

LEASE IT ONLY THROUGH THAT MECH AN ISM AN D RELEASE

THE CARBON BACK TO THE ATMO SPHERE. IT ALSO PUTS A

WHOLE BUNCH OF CARBON ONTO THE FOREST FLOOR DEAD

TREES, DEAD BRANCH ES, AND SO ON WH ICH ARE THEN

EATEN BY THE AN IMALS THAT LIVE ON TH E FOREST FLOOR,

DECOMPOSED BY THE MACROFUNGI AN D THE OTHER PRO-

CESSES ON THE FOREST FLOOR. AND THAT RESPIRATION FROM

THOSE ORGANISMS RELEASES CARBON DIOXIDE BACK TO THE

ATMOSPHERE.\ E

BRENDON : BUT I THOU GHT THE AMOUN T OF CARBON TH AT

GOES INTO THE SYSTEM H AS TO EQUAL THE AMOUN T THAT

COMES OUT.

MIKE APPS: YOUVE GOT IT. THATS THE CON SERVATION LAW.

BUT ITS NOT NECESSARILY ALL THAT GOES IN HAS TO COME

OUT. ITS TH E DIFFERENCE BETWEEN WH AT GOES IN AN D

COMES OUT, AN D REMAINS THERE. CARBON CAN T BE CRE-

ATED OR DESTROYED. SO THE CARBON THAT CAME IN, EITHER

REMAINS IN TH E SYSTEM ON THE FOREST FLOOR, OR IN THE

SOILS, OR IN THE TREES OR IS RESPIRED BACK OUT TO THE

ATMOSPHERE THROUGH FIRE AND THROUGH TH E DECOMPO-

SITION PROCESSES OF ANIMALS LIVING OFF IT. SO CONSERVA-

TION IS WHAT ITS ABOUT. IT HAS TO STAY SOMEWH ERE, AN D

WE HAVE TO ACCOUNT FOR ALL OF IT.

TARA: SO WHEN A TREE GROWS, IT USES PH OTOSYNTHESIS TO

TURN CARBON DIOXIDE INTO PLAN T MATERIAL. AND WHEN

IT BURNS, THE PROCESS IS REVERSED. SOME OF THE MASS GOES

UP THE CHIMN EY IN TH E FORM OF COMBUSTION GASES, AND

SOME IS REDUCED TO ASH.\ E BUT ITS

ALL ACCOUN TED FOR.

JENNIFER: TAKE TWO FLASKS. LABEL THEM A AN D B. FILLB WITH GRASS CLIPPINGS.

JOH N: SUSPEND A THERMOMETER IN EACH. USE COTTON

WOOL IN TH E NECKS TO HO LD THE THERMOMETER.


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JENN IFER: AN D RECORD THE TEMPERATURE OF EACH.

JOH N: LEAVE THEM BOTH FOR A DAY OR TWO, THEN CHECK

THE TEMPERATURES AGAIN.

JENN IFER: WHAT DO YOU THINK WILL HAPPEN?

TARA: SCIENTISTS PUT ALL FORMS OF ENERGY INTO GROUPS,

THOSE THA T SHO W MOTION AN D THOSE THAT DON T. IF IT

MOVES, WE SAY IT HAS KINETIC ENERGY.

SAMMY: KINETIC. ITS FROM THE GREEK WORD KIN ETIKOS.

IT MEANS MOTION.

TARA: KINETIC ENERGY IS MOTION. SO THE FASTER AN O B-

JECT MOVES, THE MORE KINETIC EN ERGY IT HAS.

FRED: KINETIC EN ERGY IS ALSO RELATED TO MASS. IF TWO

OBJECTS ARE TRAVELING AT THE SAME SPEED, THE ONE WITH

MORE MASS WILL HAVE MORE KINETIC ENERGY.

DAN A: THE RELATION SHIP BETWEEN KINETIC ENERGY, MASS,

AN D SPEED IS REPRESENTED BY THE EQUATION: EK EQUALS

1/ 2 MV SQUARED, WHERE

EK IS THE KINETIC ENERGY OF THE O BJECT, M IS THE

OBJECTS MASS, AND V IS THE OBJECTS SPEED. OKAY, JOH N.

SUPPOSE JENNIFER RIDES HER BIKE AT 3.0 METERS PER SECOND.

HO W MUCH KINETIC ENERGY WOULD SHE AN D THE BIKE

HAVE?

JOHN : WELL, THE FORMULA FOR KINETIC ENERGY IS:

DANA: RIGHT.

JENN IFER: AND MY BIKE HAS A MASS OF 12.3 KILOGRAMS, AND

IM 54 1/ 2 KILOGRAMS. SO THE TOTAL MASS IS

JOH N: 66.8 KILOGRAMS. AND YOU SAID THA T V IS EQUAL TO

3.0 METERS PER SECOND.

DANA: RIGHT.

JENNIFER: SO EK EQUALS:

JOHN : WHICH IS:

DAN A: NICE WORK.\ E ENERGY ON TH E MOVE IS KINETIC EN-

ERGY. THE AMOUNT OF KINETIC ENERGY A BODY OR OBJECT

HAS DEPENDS ON THE MASS OF THE BODY AND TH E SPEED AT

WH ICH IT IS TRAVELING. THE RELATION SHIP BETWEEN KI-N ETIC ENERGY, MASS, AND SPEED IS REPRESENTED BY THE

EQUATION: EK EQUALS 1/ 2 MV SQUARED.

LAUREEN: WH EN THIS CAR MOVES, IT HAS KINETIC ENERGY.


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BUT WH AT ABOUT AN O BJECT THAT ISNT MOVING? DOES IT

HA VE AN Y ENERGY AT ALL? AN D IF NOT, WHERE DOES THE

ENERGY FOR MOTION COME FROM?

TARA: SO HOW DOES THIS WORK?

STEVE COTTON : OKAY. THE WEIGHT IS CON NECTED TO THE

CHAIN , WHICH APPLIES A FORCE TO THE MECHAN ISM. THIS

MAKES THE CLOCK RUN.

TARA: SO THE KINETIC ENERGY IN TH E WEIGHT IS TRAN S-

FERRED TO TH E MECHAN ISM IN THE CLOCK, AND THATS

WHAT MA KES THE H ANDS GO ROUN D?

STEVE COTTON: THATS CORRECT. BY PULLING ON THE CHAIN,

YOU RAISE THE WEIGHT TO THE VERY TOP, AND THAT APPLIES

A FORCE TO THE MECHAN ISM. THE CLOCK RUN S UN TIL THE

WEIGHT GOES RIGHT DOWN , TOUCHES THE FLOOR, AND THEN

THE CLOCK STOPS.

DAN A: WE PULL THIS WEIGHT TO THE TOP, AND JUST BEFORE

IT STARTS TO MOVE DOWN, IT HAS NO KINETIC ENERGY. BUT

BECAUSE IT HA S THE ABILITY TO MOVE, WE SAY IT HA S PO-

TENTIAL EN ERGY. AN D ON CE IT STARTS MOVING, THE

WEIGHTS POTENTIAL EN ERGY IS TRAN SFORMED IN TO KI-

NETIC ENERGY. POTENTIAL ENERGY ENERGY THATS STORED

JUST WAITING TO BE USED.

FRED: A CHARGED BATTERY HAS STORED CHEMICAL POTEN-

TIAL ENERGY. WE RELEASE THAT POTENTIAL ENERGY AS ELEC-

TRICAL ENERGY.

TARA: WE GET OUR ENERGY FROM FOOD. PLAN TS TAKE IN

THEIR ENERGY FROM THE SUN AND USE PHOTOSYNTH ESIS TO

STORE IT AS CHEMICAL POTEN TIAL ENERGY. WH EN WE EAT

THE FOO D, OUR BODIES RELEASE THE POTEN TIAL ENERGY

AND PUT IT TO USE.

DAN A: THE KINETIC ENERGY OF THIS WEIGHT IS A RESULT OF

THE EARTHS GRAVITY ACTING ON IT. SO THE POTENTIAL EN-

ERGY OF THE WEIGHT IS CALLED GRAVITATIONAL POTENTIAL

ENERGY. IF THE MASS OF AN OBJECT IS GREATER, THE GRAVI-

TATIONAL PO TENTIAL EN ERGY INCREASES. SIMILARLY, THEGREATER THE HEIGHT...THE GREATER THE POTENTIAL EN ERGY.

GRAVITATION AL POTEN TIAL ENERGY CAN BE CALCULATED

USING THE EQUATION: EP EQUALS MGH. WH ERE EP IS THE


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GRAVITATIONAL POTENTIAL ENERGY OF THE OBJECT, MEA-

SURED IN JOULES. M IS THE MASS OF THE OBJECT, MEASURED

IN KILOGRAMS. G IS TH E ACCELERATION O F AN Y OBJECT

FALLING TOW ARD EARTH AS A RESULT OF THE GRAVITA-

TION AL FORCE. ITS MEASURED IN METERS PER SECON D

SQUARED. AND FINALLY, H IS THE OBJECTS VERTICAL DIS-

TANCE FROM THE REFERENCE POSITION. WE MEASURE THAT

IN METERS.

JOHN : WEVE GOT THREE PLASTICINE BALLS WITH DIFFERENT

MASSES: 0.02213 KILOGRAMS, 0.03960 KILOGRAMS, AND 0.08274

KILOGRAMS.

JENN IFER: WE CAN FIGURE OUT HOW MUCH GRAVITATIONAL

POTENTIAL ENERGY EACH ONE HAS BY USING THE FORMULA:

EP EQUALS MGH.

JOH N: THERE ARE THE MASSES, AND WE KNOW G IS THE AC-

CELERATION OF AN OBJECT FALLIN G TOWARD TH E EARTH

BECAUSE OF GRAVITATIONAL FORCE.

JENN IFER: WH ICH IS 9.81 METERS PER SECON D SQUARED.\ E

AN D H IS 0.916 METERS.

JOH N: SO THE GRAVITATION AL POTENTIAL ENERGY OF THE

TURQUO ISE BALL IS:

JENNIFER: WH ICH IS 0.199 JOULES.

JOHN: AND THE GRAVITATIONAL POTENTIAL ENERGY OF THE

OTH ER TWO BALLS IS

JENNIFER: 0.356 JOULES AN D 0.743 JOULES.

JOH N: NO W LETS SEE WHAT HAPPENS WHEN WE CONVERT

THE GRAVITATION AL POTENTIAL ENERGY INTO KINETIC EN-

ERGY.

DANA : ETHAN OL IS A CHEMICAL PRODUCED WH EN YEAST

BREAKS DOWN TH E SUGARS IN PLAN T MATERIAL. IT CAN BE

USED AS AN ALTERNATE FUEL SOURCE FOR AUTOMOBILES. IN

N ORTH AMERICA, ETHAN OL IS PRODUCED FROM CORN,

WH EAT, AND OTH ER GRAINS. BUT BRAZIL IS THE

WORLD LEADER IN METHA NO L USE. MILLION S OF AUTOMO-

BILES RUN ON FUEL PRODUCED FROM SUGAR CANE. ITS EVENMORE POPULAR THAN GASOLINE. IN AD DITION, FURTHER

PROCESSING PRODUCES A CHEMICAL TH AT CAN BE USED TO

MAKE PLASTICS, PAIN TS, AND SOLVENTS. THE FIBER LEFT OVER


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CAN BE BURNED AS FUEL FOR THE SUGAR FACTORY, OR USED

TO MAKE A GAS SIMILAR TO N ATURAL GAS. POTENTIAL

ENERGY...IN SUGAR CAN E.

BRENDO N: WE TALKED ABOUT THE CON SERVATION OF CAR-

BON . WH AT ABOUT ENERGY? ISNT THAT CON SERVED?

MIKE APPS: OH , YES. IN FACT, ITS A LITTLE BIT HARDER TO

SEE, BUT SOLAR ENERGY DRIVES EVERYTHING THAT WE SEE

AROUND US. SOLAR ENERGY DRIVES THE PHOTOSYNTHESIS

PROCESS, AND WE H AVE THIS SOLAR ENERGY BEING CO N -

VERTED INTO CHEMICAL ENERGY A KIND OF POTENTIAL EN-

ERGY, IF YOU LIKE. THA T CHEMICAL ENERGY IN TH E FOOD

THATS PRODUCED AT THE LEAF, THEN IS USED ALL THE WAY

DOWN THROUGH THE TREE TO MAINTAIN ITS GROWTH , TO

MAIN TAIN ITS STRUCTURE, TO MAKE THE TREE WORK. AN D

ITS THE BURNING OF FOOD, OR THE EATING OF THAT FOOD

BY THE TREE ITSELF, THAT GIVES THE RESPIRATION THAT

YOUVE HEARD ABOUT. IT ALSO ENDS UP BEING IN SOME OF

THE WOOD MATERIAL THAT ENDS UP ON THE FOREST FLOOR

THAT DRIES AND GIVES THE EN ERGY TO THE ANIMALS THA T

LIVE ON IT. SO ENERGY IS CONSERVED BY THE PH OTOSYNTHE-

SIS TURNIN G INTO CHEMICAL ENERGY, AND THEN BEING

BURNED LATER ON .

LAUREEN: POTENTIAL ENERGY. ITS THE ENERGY STORED IN

AN OBJECT. CHEMICAL POTENTIAL ENERGY BECOMES ELEC-

TRICAL ENERGY. GRAVITATIONA L POTEN TIAL ENERGY BE-

COMES KINETIC. AND THE SUGAR IN PLANTS, WITH ITS CHEMI-

CAL POTENTIAL ENERGY CONVERTED TO ETHANOL, BECOMES

THERMAL ENERGY, AN D EVENTUALLY KINETIC ENERGY.

JENNIFER: IN TH E MID-1800S, JAMES PRESCOTT JOULE BUILT A

MACH INE THAT USED WEIGHTS TO SPIN PADDLES AROUN D

IN A CON TAINER OF WATER.

JOH N : H E RECORDED THE TEMPERATURE OF THE WATER.

OURS IS 20 DEGREES CELSIUS.

JENN IFER: HE THEN SPUN THE PADDLES OF HIS MACH INE

AROUND IN THE WATER.JOH N: WH EN H E CHECKED THE TEMPERATURE OF THE WA-

TER AGAIN, HE FOU ND IT HAD INCREASED. OURS IS 20.5 DE-

GREES CELSIUS.


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JENN IFER: SO JOULE CONCLUDED THAT MECHA NICAL EN-

ERGY CAN BE CON VERTED TO THERMAL ENERGY.

DAN A: JOULE TOOK THE EXPERIMENT ONE STEP FURTHER. HE

CALCULATED HOW MUCH MECHAN ICAL ENERGY WAS

NEEDED TO SPIN THE PADDLES AND COMPARED THAT TO THE

INCREASE IN WATER TEMPERATURE. IN OTHER WORDS, HE DE-

TERMINED THE MECHAN ICAL EQUIVALENT OF HEAT. HIS

FINDIN GS FORMED THE BASIS FOR THE FIRST LAW OF TH ER-

MODYNAMICS.

RANIA: COULD YOU PLEASE EXPLAIN WHATS SPECIAL ABOUT

THIS HOUSE?

JORG OSTROWSKI: WELL, THERES MANY DIFFERENT FEATURES

ABOUT THIS HOUSE THA T ARE UNIQUE AND INTERESTING.\ E

AND ONE OF THE FEATURES IS THAT ITS BUILT TO BE TOTALLY

SELF-SUFFICIENT, WHICH MEANS THAT IT CAN OPERATE WITH-

OUT BEING CO NN ECTED TO THE SEWER, TO THE GAS LINE, OR

THE ELECTRICITY GRID. SO THIS HO USE HAS NO FURN ACE,

HAS NO GAS LINE, AND H AS NO BOILER.

RANIA: SO IT CONVERTS SOLAR ENERGY TO THERMAL ENERGY

TO HEAT THE H OUSE?

JORG OSTROWSKI: YEAH.

FRED: THE THERMAL ENERGY IN MATTER IS CAUSED BY THE

RANDOM MOTION OF MOLECULES.

TARA: WH EN TH E MOLECULES OF TWO O BJECTS ORIGI-

NALLY AT DIFFERENT TEMPERATURES COME INTO CON TACT

WITH EACH OTHER, THEY TRANSFER THERMAL ENERGY.

FRED: THE TH ERMAL ENERGY OF THE FIRE IS TRAN SFERRED

TO THE KETTLE, AND THEN TO THE WATER.

TARA: AN D SOON ITLL HEAT UP THIS CUP.

FRED: THE TRANSFER OF THERMAL ENERGY IS WHAT WE CALL

HEAT.

TARA: AN D H EAT ALWAYS FLOWS FROM WARM OBJECTS TO

COO LER ON ES. THA TS THE SECOND LAW OF THERMOD Y-

NAMICS.

RAN IA: HOW DOES THE ENERGY THA TS ABSORBED GET RE-CYCLED?

JORG OSTROWSKI: THE RADIATION AN D THE CON VECTION

PRODUCES A MICROCLIMATE INSIDE THE HOUSE. THATS VERY,


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VERY DIFFERENT FROM THE COLD WINTER WEATHER THAT IS

OUTSIDE. AND SO THE SUN HAS BEEN ABSORBED DURING THE

DAY, ON TO THE BRICK, AN D ON TO THE DA RK TILES IN TH E

FLOOR. THA T HEAT IS JUST GIVEN O FF BY RADIATION

THROUGH OUT THE ENTIRE HOUSE. AS THE AIR IS WARMED

UP, TH AT WARM A IR JUST ASCENDS, JUST BY CONVECTION ,

UNDERNEATH THE CATHEDRAL CEILING. AND THEN IT FINDS

ITS WAY THROUGH THE DUTCH DOORS ABOVE, AND THROUGH

THE GREENH OUSE, COMES DOWN THROUGH THE OPEN

DOORS IN THE HALLWAY, COMES DOWN THE STAIRS,

AN D THEN COMES BACK INTO TH IS AREA HERE, SO KEEPING

THIS AREA A LOT WARMER THAN THE CLIMATE OUTSIDE.

TARA: THE CHEMICAL POTENTIAL ENERGY IN A BURNIN G LOG

IS RELEASED AS TH ERMAL ENERGY IN THE FIRE.

FRED: THE TH ERMAL ENERGY IS TRANSFERRED TO THE

KETTLE, AND FROM THE KETTLE TO THE WATER.

TARA: BUT NO T ALL THE POTENTIAL ENERGY IN TH E LOG IS

TRANSFERRED TO THE WATER.

FRED: SOME OF THAT THERMAL ENERGY HEATS THE AIR, SOME

HEATS THESE OTHER METAL OBJECTS.

TARA: AN D SOME OF THE PO TENTIAL ENERGY IS EVEN USED

UP AS SOUND.

NATH AN: DOES THIS SOLAR HOME CAPTURE ALL THE ENERGY

YOU N EED TO HEAT AND RUN THE H OME?

JORG OSTROWSKI: THE H OUSE LOSES HEAT THROUGH WIN-

DOWS, THE ROOF, AND TH E FLOOR. AND IT HAS TO REPLACE

THAT H EAT FROM SOMEWH ERE. THE SUN PROVIDES ALL THE

BACK-UP HEATIN G THAT THE HO USE N EEDS. IT ALSO PRO-

VIDES ELECTRICITY THROUGH THE USE OF

PHOTOVOLTAICS, HOT WATER THROUGH THE SOLAR HOT

WATER COLLECTOR, AND WARM AIR THROUGH THE WINDOWS

AND THE WARM AIR SOLAR COLLECTOR. THE OTHER WAY OF

BACK-UP HEATING WH EN THERES NOT ENOUGH SUN IS

THROUGH THE USE OF THE MASONRY FIREPLACE.

FRED: SO THE THERMAL ENERGY OF A BURNING LOG IS TRANS-FERRED TO THE KETTLE AN D TO THE WATER.

TARA: THATS AN EXAMPLE OF THE SECOND LAW OF THER-

MODYNAMICS: HEAT ALWAYS FLOWS FROM A WARM OBJECT


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TO A COOLER ONE.

FRED: ALTHOU GH TH E BURNIN G LOG BOILS THE WATER IN

THE KETTLE, IT ALSO H EATS THE AIR, THE FIREPLACE, AND THE

KETTLE.

TARA: THATS BECAUSE DURING AN Y ENERGY CON VERSION ,

USEFUL ENERGY IS LOST.

DAN A: SO AS SCIENTISTS CON TINUE TO EXPERIMENT, THEY

DEVELOP THEORIES TO EXPLAIN H OW N ATURE WORKS. THE

LAW O F CON SERVATION O F MASS STATES THA T MATTER

CAN N OT BE CREATED OR DESTROYED. THE FIRST LAW OF

THERMODYNAMICS SAYS ENERGY CANNOT BE CREATED OR

DESTROYED, ON LY CON VERTED FROM ON E FORM TO A N-

OTHER. THE SECOND LAW OF THERMODYNAMICS TELLS US

HEAT GOES FROM MATTER AT A H IGH TEMPERATURE TO MAT-

TER AT A LOWER TEMPERATURE. AND IN EVERY TYPE OF EN-

ERGY CONVERSION, SOME USEFUL ENERGY IS CONVERTED TO

THERMAL ENERGY, WHICH IS NO LONG ER USEFUL. WE SAY

THE EN ERGY IS LOST BECAUSE THE AMOUN T OF USEFUL EN-

ERGY HAS DECREASED. THE FACT THAT ENERGY IS LOST ON

EVERY ENERGY CON VERSION MEAN S THAT PO TENTIAL EN-

ERGY CAN NEVER BE COMPLETELY CON VERTED TO KIN ETIC

ENERGY. INSTEAD, SOME OF IT BECOMES THERMAL ENERGY

OR SOUND ENERGY. AND THATS WHY THE SEARCH FOR A PER-

PETUAL MOTION MACH INE HAS PROVED FUTILE.

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