THE SCIENTIST

METHOD 3º ESO

SERGIO SALOBREÑA

LUCENA

FUENGIROLA

THE SCIENTIST METHOD

•THE SCIENTIFIC METHOD IS A PROCEDURE THAT HAS

CHARACTERIZED SCIENCE SINCE THE XVII CENTURY, WHICH

CONSISTS OF SYSTEMATIC OBSERVATION, MEASUREMENT,

EXPERIMENTATION, FORMULATION OF HYPOTHESIS,

ANALYSIS OF HYPOTHESIS AND MODIFICATION OF

HYPOTHESES. THIS METHOD ALWAYS FOLLOWS THE SAME

PHASES:

1. FIND A PROBLEM: AFTER OBSERVING NATURE APPEAR

THE QUESTION : WHY SOMETHING HAPPENS?. EXAMPLE:

WHY DOES LIGHTNING APPEAR IN HEAVEN?

THE SCIENTIST METHOD

2. FORMULATION OF THE HYPOTHESIS: IT IS THE POSSIBLE

ANSWER TO THE PREVIOUS QUESTION. EXAMPLE: THE

LIGHTNINGS ARE AN ELECTRIC SHOCK THAT HAPPENS

NATURALLY IN A STORM.

3. CHECKING THE HYPOTHESIS:

A)PLAN AN EXPERIMENT WITH WHICH YOU CAN CHECK IF

YOUR HYPOTHESIS IS CERTAIN: FOR EXAMPLE, YOU PLACE A

LIGHTING ROD JOINED TO AN ELECTRIC METER AND

OBSERVE THAT EFFECTIVELY, WHEN A RAY REACHES THE

OBJECT IT IS MEASURED A LARGE ELECTRICAL DISCHARGE.

THE SCIENTIST METHOD

B. OBTAINING AND ANALYZING DATA: AFTER MEASURING THE

ELECTRICAL DISCHARGES RECORDED IN A STORM NIGHT,

WE ORGANIZE THE DATA IN A TABLE AND OBSERVE IF THE

DATA OBTAINED ARE THE EXPECTED ACCORDING TO OUR

HYPOTHESIS.

4. EXTRACTION OF CONCLUSIONS: YOU OBSERVE THAT YOUR

HYPOTHESIS IS TRUE, EVERYTIME THAT ANY RAY

REACHES THE LIGHTING ROD YOU REGISTER AN

ELECTRIC DISCHARGE.

5. COMMUNICATION OF RESULTS: YOU MAKE A REPORT IN

WHICH IT REFLECTS THE DEVELOPMENT OF YOUR

INVESTIGATION AND YOUR RESULTS, AND EXPLAINS IT IN

THE COLLEGE AND ANY SCIENCE MAGAZINE.

THE SCIENTIST METHOD

DATA TABLES AND GRAPHICS ARE USED FOR THE INTERPRETATION OF DATA.

FROM A GRAPHIC, WE CAN PREDICT THE VALUES THAT ARE LOCATED

AMONG THE STUDENTS VALUES, THAT IS TO INTERPOLATE, AND PREDICT

THE VALUES THAT ARE LOCATED OUTSIDE THE STUDENTS VALUES OR

EXTRAPOLATE. THE FORM OF THE LINE SHOWS THE RELATIONSHIP

BETWEEN THE VARIABLES.

THE MOST USUAL GRAPHICS

1. STRAIGHT LINE PASSING THROUGH THE ORIGIN: IT INDICATES THAT WHEN

THE VARIABLE X INCREASES, SO DOES THE VARIABLE Y. THIS RELATION

IS EXPRESSED BY THE FOLLOWING EQUATION: Y=aX. a IS A CONSTANT,

WHICH INDICATES HOW MUCH GROWS Y WITH RESPECT TO X. IF a=2, THE

DEPENDENT VARIABLE (Y) WILL GROW TWICE AS MUCH AS THE

INDEPENDENT VARIABLE (X).

THE MOST USUAL GRAPHICS

2. STRAIGHT LINE THAT DOES NOT PASS THROUGH THE ORIGIN: IT

INDICATES THAT WHEN THE VARIABLE X INCREASES, SO DOES THE

VARIABLE Y, BUT WE ADD b, WHICH IS THE POINT WHERE THE LINE CUTS

THE Y-AXIS. Y= aX+b.

THE MOST USUAL GRAPHICS

3. HYPERBOLA: A HYPERBOLA SHOWS THAT THE DEPENDENT VARIABLE (Y)

DECREASES WHEN THE INDEPENDENT VARIABLE (X) INCREASES. THEY

ARE SAID TO BE INVERSELY PROPORTIONAL. THE RELATION BETWEEN

THEM IS A CONSTANT (K) WHICH INDICATES HOW MUCH ONE DECREASES

AS THE OTHER INCREASES. THE EQUATION THAT CHARACTERIZES IT IS:

THE MOST USUAL GRAPHICS

4. PARABOLA: THIS GRAPH SHOWS THAT THE DEPENDENT VARIABLE (Y)

INCREASES GREATLY WHEN THE INDEPENDENT VARIABLE (X) INCREASES.

THIS IS BECAUSE Y VARIES WITH THE SQUARE OF X, SO THAT AS X HAS A

SMALL INCREASE, Y TRIGGERS ITS VALUE. Y=aX2.

FORMULATION OF LAWS AND THEORIES

•. A LAW IS A HYPOTHESIS CONFIRMED BY MULTIPLE EXPERIMENTS. CAN BE

EXPRESSED THROUGH AN EQUATION OR AS A PRINCIPLE.

• THEORIES ARE BUILT TO MAKE RELIABLE PREDICTIONS ON EVEN EVOLVING

PHENOMENA.

• THE MODELS SERVE TO EXPLAIN THE PHENOMENA IN A SIMPLIFIED

MANNER. USUALLY, THEY HAVE AN EDUCATIONAL PURPOSE.

MAGNITUDES AND UNITS

ALL OF THOSE PROPERTIES OF THE BODIES THAT WE CAN MEASURE ARE

MAGNITUDES.

TO MEASURE A MAGNITUDE IS TO COMPARE IT WITH ANOTHER QUANTITY

THAT WE USE AS A REFERENCE AND THAT WE CALL UNITY. FOR EXAMPLE,

THE UNITY KILOGRAM IS THE WEIGHT OF A PLATINUM AND IRIDIUM CYLINDER

THAT IS KEPT IN THE OFFICE OF WEIGHTS AND MEASURES OF PARIS.

WHEN WE SAY THAT DAVID'S BACKPACK HAS A WEIGHT OF 3 Kg, IT MEANS

THAT IT CONTAINS 3 TIMES THE WEIGHT UNIT: THE KILO. THE MEASURE IS 3

AND THE UNIT THE KILOGRAM (Kg).

TO MEASURE MAGNITUDES, MEASURING INSTRUMENTS, SUCH AS THE

METRIC TAPE, THE BALANCE, THE THERMOMETER OR THE PLUVIOMETER,

ARE USED.

THE INTERNATIONAL SYSTEM OF UNITS

IN 1960, THE INTERNATIONAL SYSTEM OF UNITS (SI) WAS ESTABLISHED.

CONSISTS OF 7 FUNDAMENTAL BASIC MAGNITUDES, WHICH CAN BE

MEASURED DIRECTLY, AND FROM WHICH OTHER DERIVATIVE MAGNITUDES

ARE OBTAINED. FOR EXAMPLE, FROM THE LENGTH AND THE TIME CAN BE

ACHIEVED THE SPEED DERIVED MAGNITUDE.

CONVERSION FACTORS

TO TRANSFORM UNITS IN OTHERS WE WILL USE THE CONVERSION FACTORS.

A CONVERSION FACTOR IS A FRACTION WHO EXPRESSING THE

EQUIVALENCE BETWEEN TWO UNITS.

1kg

▬

1000 g

IF WE WANT TO PASS 3000 Km TO THE INTERNATIONAL SYSTEM

1. WE ARE LOOKING FOR EQUIVALENCE BETWEEN Km and m (SI). 1Km = 1000

m 1000m

▬▬

1Km

2. WE MULTIPLY THE MEASURE BY THE CONVERSION FACTOR :

3000 Km x 1000 m

▬▬ = 3000000 m

1 Km

CONVERSION FACTORS

TO OPERATE WITH CONVERSION FACTORS IN DERIVATIVE MAGNITUDES LIKE SPEED, WE WILL DO IT IN

THE FOLLOWING FORM:

EXPRESS IN SI UNITS 80 Km/h

1. WE KNOW THAT THE UNIT OF THE INTERNATIONAL SYSTEM FOR SPEED IS m / s. SO WE WILL NEED 2

CONVERSION FACTORS, ONE THAT RELATES Km with m AND ANOTHER THAT RELATES h with s.

2. WE CREATE OUR CONVERSION FACTORS:

WE ALWAYS CREATE OUR CONVERSION FACTORS SO THAT THEY OPPOSE THE AMOUNT THAT WE

HAVE TO CONVERT. OBSERVE Km IS IN THE NUMERATOR SO THAT IN THE CONVERSION FACTOR

WE WILL SITUATE IT IN THE DENOMINATOR; AND HOUR IS IN THE DENOMINATOR SO THAT IN THE

CONVERSION FACTOR WE WILL SET IT IN THE NUMBERER. IN THAT WAY THE REPEATED UNITS

CANCELS AND YOU OBTAIN WHAT YOU WANTED: m / s.

3. WE OPERATE AS IN THE PREVIOUS EXAMPLE:

Km

m

1

1000

s

h

3600

1

sms

m

s

h

mK

m

h

mK/22,22

3600

80000

3600

1

1

100080

SCIENTIFIC NOTATION

IT IS USED TO AVOID WORKING WITH LARGE NUMBERS. IT IS TO EXPRESS THE NUMBERS

AS POTENTIALS OF 10.

STEP 1: WE WILL WRITE THE NUMBER WITH A SINGLE WHOLE DIFFERENT NUMBER OF 0

IN FRONT OF THE COMA. FOR THAT WE MOVE THE COMA:

A) 7856.1 ---- 7.8561 B) -0.005612 ----- -5,612

STEP 2: WE MULTIPLY THE AMOUNT FOR A POTENTIAL OF 10.

A) 7.8561 X 10 B) -5.612 X 10

STEP 3: THE EXPONENT OF 10 WILL BE EQUAL TO THE NUMBER OF POSITIONS THAT WE

HAVE MOVED THE COMA.

A) 7,8561 X 103 B) -5,612 X 103

STEP 4: IF WE HAVE MOVED THE COMA TO THE LEFT THE EXPONENT WILL BE POSITIVE,

AND IF WE HAVE MOVED IT TO THE RIGHT IT WILL BE NEGATIVE.

A) 7,8561B X 103 B) -5,612 X 10-3

ROUNDING

IT IS USED WHEN A RESULT HAS MANY DECIMAL FIGURES. WE WILL ROUND

THE DECIMAL NUMBER THAT TELLS US THE PROBLEM, AND IF IT DOES NOT

INDICATE ANYTHING WE WILL ROUND TO THE SECOND DECIMAL NUMBER.

STEP 1: WE TAKE THE DECIMAL FIGURES THAT THE PROBLEM INDICATES OR

WE ROUND TO THE CENTURIES:

A) 0,5432 B) 567,895 C) 1347,73654429

STEP 2: IF THE FOLLOWING NUMBER IS 5 OR MORE, WE WILL INCREASE ONE

UNIT THE LAST NUMBER IN RED. IF IT IS LESS THAN 5, WE LEAVE IT THE

SAME. IN BOTH CASES WE DESPISE ALL THE OTHER DECIMALS.

A) 0.54 B) 567.90 C) 1347.74