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Science Basics.

posted Nov 3, 2016, 2:30 PM by Upali Salpadoru   [ updated Aug 31, 2017, 12:21 PM ]

There are a few basic facts, skills and attitudes that everybody has to master in addition to 3 Rs.

They are specified and defined in the field of ....SCIENCE.


  1. What is science ?

  • An attempt to understand our environment and various phenomenon using our senses. ( Not by imagination).

  • To pass on the acquired knowledge and skills to the generations that follow.

  • To apply the knowledge and skills for the benefit of man.



  1. What is essential to achieve these?

  • Better communication. Common symbols, Definitions and concepts.

  • A uniform system of measurements.  We use ;System International ( SI. )

                     

  1. We accept the following:

  • Our senses give us the correct information.

                      There are limitations.

  • Our hypotheses, theories and Laws  may not be the ultimate truth but the best available at the present time.



Basic Concept and Definitions in Science.

According to alphabetical order.

                 Vector quantities should have a direction. Others are scalars.

A

Term

 Meaning/definition

Acceleration:- 

 Rate of changing velocitySI unit  = meters per second per second.   mS-2.

Atom:-

 The smallest unit that can exhibit the properties of an element. An atom has 2 identifying numbers. Atomic number and atomic mass.

Atomic mass:-

 This is equal to the sum of the particles in the nucleus; namely protons and neutrons.

Atomic number:-

 Gives the number of protons in the atom. This is equal to the number of electrons in orbit. Visit:- Atoms and Molecules.

  


B

Basic SI units:-

Measurement.

Measuring Instrument. 

Unit

Symbol.

Length.

Meter.

m.

Mass.

Kilogram

Lg.

Time

Second

s

Current.

Ampere.

A.

Luminosity.

Candela

Cd.

Amount of substance.

Mole.

Mol.

Temperature.

Kelvin.

K.


C

 Compounds:- Substances having more than one kind of atom, bonded by chemical bonds or electrical attractions in the case of ionic compounds.  
 Elements obey the law of definite proportions unlike in the case of mixtures.
Eg. Water. Salt, Rust, Sand, Protein, sugar.             Click:- Mix. and compounds.

                 

D

 Density:-

 Displacement:-
 Distance:-
 Mass of one unit volume of a substance. SI. Unit    kgm-3   or  gcm-3                Density = Mass/ Volume.
 This gives the shortest distance between two places.  SI unit  Meter with direction. m. A Vector quantity.  The space one has to travel, in a straight or a crooked line, from one place to another. Eg, From your home to school. A scalor quantity. SI unit  Meter.   m.   (Length although synonymous we refer to a dimension of an object.)

 

E

 Elements:-
 
 Energy
:-
 A substance consisting of only one kind of atoms. All the elements are arranged in the Periodic Table. Click here to read.
 Usually defined as the ability to do work.
So work and energy are measured in the same units.Si unit = Joule.  J.

                 



Energy Type

Remarks

Examples

Chemical   energy,

Energy absorbed or released during chemical changes.

Burning. Rusting. Digesting.

Radiant energy.

Energy that can travel in space at a velocity of 3x108 ms-1.

Electromagnetic waves such as Radio and TV waves. Light, X ’rays.

Electrical energy.

Due to electron flow or electrical charges.

Domestic lighting cooking.

Lightening.

Atomic energy,

Energy stored in the nucleus of atoms.

Radioactivity. As coming from, Sun, atom bombs and the core of earth.

Mechanical energy.

a. Kinetic energy.

b. Potential energy.

c. Vibrational.

d.Thermal energy.

  1. Present due to motion.

  2. Stored up energy.

  3. As in mechanical waves.

  4. Rapid movement of atoms and molecules.

  1. Wind, Water falls.

  2. Clouds. Wound spring.

  3. Sound.

  4. Heat.


              

F

 Frequency:

 Force:-
 Number of occurrences in one second. Eg. Vibration of a tuning fork. SI. Unit = Hertz.  Hz. Ability to change the velocity of a body.
The ability to change the velocity of a body.   SI unit= Newton.    N   

    Types of Force.

                    

Name.

Examples.

Remarks.

Friction.

Forces that restrict motion.

Contact friction:-  static, sliding and rolling.

Fluid friction:- in air. In water.

Repulsions:-  

Electrical and Magnetic

Electrical:-

+,charge and a +, charge.

_  charge and a_ charge.

Magnetic:-.

N pole and a N pole.

S pole and a S pole.

Attractions:-    

Electrical, Magnetic, Gravitational.

Electrical:-

+,charge and a _  charge.

Magnetic:-

N pole and  a S pole.

Gravitational:-

Earth and moon.

Muscular    forces:-

Push, pull, kick etc.

A horse pulls a carriage.

Elastic forces:     

Reaction forces, (Support force, or Normal force)  

Head hits a wall, wall hits the head.

Force= Mass x Acceleration.     F= m.a.



There are only 4 Fundamental forces according to New theories in Physics.

         !. Gravity. 2. Electromagnetic.

         3. Strong nuclear, : -This holds the protons and neutrons together in the nucleus.

         4. Weak nuclear:- This is responsible for Radioactivity.


G

  G:-

Gravity.b(g)
 Gravitational constant.    About 6.67 x  10-11 m3 kg-1 s-2  
Eg. Attraction between two massive bodies =   G x m1 xm2 / radius 2.
 Pl. note that this is a very, very small number.
Gravitational attraction. Force of attraction on a body at the surface of the earth= 9.8 ms-1

           .

H

 Heat:-  This is also termed as 'Internal energy' or 'Thermal energy' The kinetic energy present due to movements and vibrations of individual atoms and molecules. Some electromagnetic rays are also often referred to as heat rays. They are infra red rays. Click Electromagnetic spectrum. Unit of measurement Joule.

I

J

K

L

M

 Magnetism:-






Magnetic Lines of force. Magnetism of Earth.(Terrestrial magnetism)-
 Attractive and repulsive forces created by electromagnetism. Some materials can be made to become permanent or temporary magnets.A magnet has 2 poles, North pole and South pole and magnetic force of lines extending from N to S.
North pole- This on the  side of the magnet that turns toward the North pole of the earth. Click- Magnets.Magnetism.
The path an imaginary N- pole of a magnet will move.


Mag..jpg

 Please Note: In the case of the earth the direction of magnetic lines is opposed to that of normal magnets.

Fig-Magnetic field of the earth.

 Mass:-


Mass is the reluctance of matter to accelerate. .Si unit = kilogram.  Kg.

 Mass of sub atomic particles.

Particle

Symbol

Mass kg.    a.m.u.

Charge

Electron.

e-.

9.109 × 10-31

 

0

 -1

Proton

P+

1.673 × 10-27

1

+1

Neutron

No

1.675 × 10-27

1

 0

a.m.u.= Atomic mass unit.

            

 Matter:-

  states of matter


Mixture :-




Mole:-

Matter      changes:-
 Everything has mass and volume. (Although Light energy  may also be considered as a stream of particles, it is not generally considered as matter.) There are 5 states of matter.  Solid, Liquid, Gas, Plasma, Bose-Einstein.

A mixture has more than one pure substance mixed. They can generally be separated by physical methods.
  Eg. Concrete, Sea water, Air,  Soil.

Si unit for the quantity of particles. If the molar mass of a chemical is measured in grams it will have 1 mol of molecules.
Refers to the Avagadro number of particles. =  6.022140857 ×1023.

Matter can change physically or chemically.
Physical changes:
- Only the arrangement of atoms or molecules change. The substance remains the same.
Eg. Changes of state, Passing a current through a conductor. Cutting wood.
Chemical changes:-
Atoms and molecules break and make new bonds. Substance changes into one or more new substances. Eg. Burning,  Rusting, Photosynthesis. Respiration.Boiling an egg.

                      

N

 Neutralization:;- Acids have pH less than 7 whiles Bases have a pH greater than 7. When they react in a proper proportion it is possible to get a solution of pH 7.
This is supposed to be the neutral state.
 Reaction:    Acid  +  Base   Salt + Water. Click- Acids and bases.


O

P

 Period:- 
 Pressure:-
 Time taken for a single event. Eg. One oscillation. For a  single cycle. Force per unit area.  
  For solids   Pressure = Mass / area receiving pressure.  P = f/ a.    For liquids   Pressure =  Height x density x gravity.     P = hdg.
  For atmospheric and gas pressure -Determined by Barometers or manometers.

Q

R

 Reaction:-  "Every action has an equal and opposite reaction." This refers to the act that forces exist in pairs. Visit Newtons Laws.

S

 Speed:-This is the rate of changing distance or displacement.      Speed =  Distance / time.    SI. unit=  ms-1      
A scalar quantity

T

 Theory:-








Time:-
 A generalization of a few natural observed or proven phenomenon.
  A few scientific Theories.
1.  Atomic theory.  John Dalton.
2.  Heliocentrism: (Sun at the centre of the solar system) Copernicus, 1543. 3. Organic evolution by natural selection: Charles Darwin, 1859.
4.  Special relativity: Albert Einstein, 1905
5.  General relativity: Einstein, 1915 6.  Quantum theory: Max Planck, Einstein, Niels Bohr, Werner Heisenberg, Erwin Schrödinger, Max Born, Paul Dirac, 1900–1926
 This may mean the time of the day or time taken to do something. (Period) 

U

 Universe:-  Everything around us; all matter, energy, space , time and various phenomenon. Known Universe-Diameter = 93 billion light-years,   

V

 Velocity:-


 
Volume:-
 The rate of changing displacement.                 
 Velocity = Displacement / Time.
  SI. unit=  ms-1      A vector quantity.

The space occupied by a certain quantity of matter.

                 Si unit = cubic meter.   m3


W

 Work:-  Spent Energy= Useful work done + wasted energy. When one kind of energy gets converted to another form work would have been done  SI. Unit= Joule. J. Work = Force x Distance moved in the same direction. W - fxd.

Waves:-

Vibration results in spreading energy using matter or without as in space.

Matter waves ( Mechanical waves)

Unable to travel in vacuum or space.

Eg.  Water waves, sound waves, seismic waves

Electromagnetic waves

Travels in space at 300 000km per second.  

Eg. Light , Radio waves.

Click:-   Electromagnetic spectrum

Longitudinal waves:

Particles vibrate parallel to the wave direction.

Eg: Sound.

Transverse waves.

Particles vibrate perpendicular to the wave direction

Eg. Water wave



X

 Xylem Cells that take water from a plant root to the shoot system.

Y

Z

       


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