So you are here probably because you want to get a deeper meaning an concept of scientific investigation.
You should have probably been familiar with the steps involved in scientific investigation i.e. Identifying problem, making hypothesis, generating data etc...
However, what I would like to emphasis in this post is the different types of variable.
You should know that "A variable is a quantity that varies in value". It represents "something" that are involved in a measurement in scientific investigation. Thus, a proper scientific investigation always involve variables and its measurement. A quantity that can be measured is called a physical quantity.
Three types of variables are:
Manipulated variable is a variable that is set or fixed before and experiment is carried out. it is usually plotted on x- axis.
Responding variable is a variable that changes according to and dependent to manipulated variable. it is usually plotted on y-axis.
Fixed variable is fixed and unchanged throughout the experiment.
Now lets see how to make inference and hypothesis?
How to make inference and hypothesis?
Inference: state the relationship between two VISIBLE QUANTITIES in a diagram or picture.
Hypothesis: state the relation ship between two MEASURABLE VARIABLES that can be investigated in a lab.
How to tabulate data?
-the name or the symbols of the variables must be labelled with respective units.
-all measurements must be consistent with the sensitivity of the instruments used.
-all the calculated values must be correct.
-all the values must be consistent to the same number of decimal places.
A graph is considered well-plotted if it contains the following:
- a title to show the two variables and investigation.
- two axes labelled with correct variables and units
- scales must be chosen carefully and graph must occupy more than 50% of the graph paper.
- all the points are correctly drawn.
- the best line is drawn.
Showing posts with label SPM Physics notes. Show all posts
Showing posts with label SPM Physics notes. Show all posts
2007-09-20
2007-09-19
SI UNITS In DeTAIL
The International System of Units, universally abbreviated SI (from the French Le Système International d'Unités), is the modern metric system of measurement. The SI was established in 1960 by the 11th General Conference on Weights and Measures (CGPM, Conférence Générale des Poids et Mesures). The CGPM is the international authority that ensures wide dissemination of the SI and modifies the SI as necessary to reflect the latest advances in science and technology.
Definitions of the SI base units
The SI is founded on seven SI base units for seven base quantities assumed to be mutually independent
Base quantity Name Symbol
length meter m
Description
The meter is the length of the path travelled by light in vacuum during a time interval of 1/299 792 458 of a second.
mass kilogram kg
Description
The kilogram is the unit of mass; it is equal to the mass of the international prototype of the kilogram - Pavillon de Breteuil (Sèvres).
time second s
Description
The second is the duration of 9 192 631 770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the cesium 133 atom.
electric current ampere A
Description
The ampere is that constant current which, if maintained in two straight parallel conductors of infinite length, of negligible circular cross-section, and placed 1 meter apart in vacuum, would produce between these conductors a force equal to 2 x 10-7 newton per meter of length.
thermodynamic temperature kelvin K
Description
The kelvin, unit of thermodynamic temperature, is the fraction 1/273.16 of the thermodynamic temperature of the triple point of water.
amount of substance mole mol
Description
1. The mole is the amount of substance of a system which contains as many elementary entities as there are atoms in 0.012 kilogram of carbon 12; its symbol is "mol."
2. When the mole is used, the elementary entities must be specified and may be atoms, molecules, ions, electrons, other particles, or specified groups of such particles.
luminous intensity candela cd
Description
The candela is the luminous intensity, in a given direction, of a source that emits monochromatic radiation of frequency 540 x 1012 hertz and that has a radiant intensity in that direction of 1/683 watt per steradian.
Definitions of the SI base units
The SI is founded on seven SI base units for seven base quantities assumed to be mutually independent
Base quantity Name Symbol
length meter m
Description
The meter is the length of the path travelled by light in vacuum during a time interval of 1/299 792 458 of a second.
mass kilogram kg
Description
The kilogram is the unit of mass; it is equal to the mass of the international prototype of the kilogram - Pavillon de Breteuil (Sèvres).
time second s
Description
The second is the duration of 9 192 631 770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the cesium 133 atom.
electric current ampere A
Description
The ampere is that constant current which, if maintained in two straight parallel conductors of infinite length, of negligible circular cross-section, and placed 1 meter apart in vacuum, would produce between these conductors a force equal to 2 x 10-7 newton per meter of length.
thermodynamic temperature kelvin K
Description
The kelvin, unit of thermodynamic temperature, is the fraction 1/273.16 of the thermodynamic temperature of the triple point of water.
amount of substance mole mol
Description
1. The mole is the amount of substance of a system which contains as many elementary entities as there are atoms in 0.012 kilogram of carbon 12; its symbol is "mol."
2. When the mole is used, the elementary entities must be specified and may be atoms, molecules, ions, electrons, other particles, or specified groups of such particles.
luminous intensity candela cd
Description
The candela is the luminous intensity, in a given direction, of a source that emits monochromatic radiation of frequency 540 x 1012 hertz and that has a radiant intensity in that direction of 1/683 watt per steradian.
Understanding Derived and Base Quantities
Understanding Derived and Base Quantities
Physical quantities are quantities that can be measured. e.g. Length, Temperature, Speed, Time.
Quantities or qualities that cannot be measured are not physical quantities. e.g. happiness, sadness etc.
Physical quantities can be divided into Base quantitied and Derived quantities.
(i) Physical quantities are quantities that can be measured or can be calculated.
(ii) The base quantities are “building block” quantities from which other quantities are derived from.
(iii) The base quantities and their S.I. units are:
(iii) Derived quantities are quantities derived (iv) Examples of derived quantities.
Standard Notation: To express very large or very small numbers.
Example; A X 10 n (ten to the power of n), n must be an integer and 1 ≤ A
Physical quantities are quantities that can be measured. e.g. Length, Temperature, Speed, Time.
Quantities or qualities that cannot be measured are not physical quantities. e.g. happiness, sadness etc.
Physical quantities can be divided into Base quantitied and Derived quantities.
(i) Physical quantities are quantities that can be measured or can be calculated.
(ii) The base quantities are “building block” quantities from which other quantities are derived from.
(iii) The base quantities and their S.I. units are:
- Base quantities S.I. units
- Mass kg
- Length m
- Time s
- Electric current A
- Thermodynamic
- temperature K
(iii) Derived quantities are quantities derived (iv) Examples of derived quantities.
- Derived quantities S.I. units
- area m2
- density kg m-3
- weight N
- velocity m s-1
Standard Notation: To express very large or very small numbers.
Example; A X 10 n (ten to the power of n), n must be an integer and 1 ≤ A
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