General Science: Fundamentals of Physics, Chemistry, and Biology

Physics: Fundamentals

Physics is the natural science that studies matter, its fundamental constituents, its motion and behavior through space and time, and the related entities of energy and force. It is one of the most fundamental and interdisciplinary branches of science. Understanding the basic principles of physics is crucial for comprehending many natural phenomena and technological advancements.

1. Mechanics

Mechanics is the branch of physics concerned with the motion of bodies under the action of forces. It is divided into statics (the study of bodies at rest) and dynamics (the study of bodies in motion).

a. Kinematics

Kinematics describes motion without considering the forces that cause it. Key concepts include displacement, velocity, and acceleration.

• Displacement: The change in position of an object. It is a vector quantity.
• Velocity: The rate of change of displacement. It is also a vector quantity (velocity = displacement / time).
• Acceleration: The rate of change of velocity. It is a vector quantity (acceleration = change in velocity / time).

The fundamental equations of motion for constant acceleration are:

v = u + at

s = ut + 0.5at²

v² = u² + 2as

Where:

• v = final velocity
• u = initial velocity
• a = acceleration
• t = time
• s = displacement

b. Dynamics

Dynamics deals with the motion of objects and the forces that cause this motion. It is governed by Newton's Laws of Motion.

• Newton's First Law (Law of Inertia): An object at rest stays at rest and an object in motion stays in motion with the same speed and in the same direction unless acted upon by an unbalanced force.
• Newton's Second Law: The acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass. Mathematically, F = ma (Force = mass × acceleration).
• Newton's Third Law: For every action, there is an equal and opposite reaction.

c. Work, Energy, and Power

• Work: Done when a force causes a displacement. Work = Force × Displacement (in the direction of the force). Unit: Joule (J).
• Energy: The capacity to do work. Types include kinetic energy (energy of motion) and potential energy (stored energy). Unit: Joule (J).
• Kinetic Energy (KE): KE = 0.5mv²
• Potential Energy (PE): PE = mgh (gravitational potential energy)
• Power: The rate at which work is done or energy is transferred. Power = Work / Time. Unit: Watt (W).

d. Gravitation

Newton's Law of Universal Gravitation states that every particle attracts every other particle in the universe with a force that is directly proportional to the product of their masses and inversely proportional to the square of the distance between their centers.

F = G (m₁m₂ / r²)

Where G is the gravitational constant.

2. Properties of Matter

This area covers the characteristics and behavior of materials.

a. Density

Density is mass per unit volume. Density (ρ) = Mass (m) / Volume (V).

b. Pressure

Pressure is force applied perpendicular to the surface of an object per unit area. P = F / A.

c. Buoyancy and Archimedes' Principle

Archimedes' Principle states that a body immersed in a fluid experiences an upward buoyant force equal to the weight of the fluid displaced by the body. This explains why ships float.

d. Surface Tension

Surface tension is the tendency of liquid surfaces to shrink into the minimum surface area possible. It is caused by cohesive forces between liquid molecules.

e. Viscosity

Viscosity is a measure of a fluid's resistance to flow. Honey is more viscous than water.

3. Heat and Thermodynamics

This branch deals with heat, temperature, and their relation to energy and work.

a. Temperature and Heat

• Temperature: A measure of the average kinetic energy of the particles in a substance. Measured in Celsius (°C), Fahrenheit (°F), or Kelvin (K).
• Heat: The transfer of thermal energy between systems due to a temperature difference. Measured in Joules (J) or calories (cal).

Conversion formulas:

• °C to °F: (°C × 9/5) + 32
• °F to °C: (°F - 32) × 5/9
• °C to K: °C + 273.15

b. Modes of Heat Transfer

• Conduction: Heat transfer through direct contact, common in solids.
• Convection: Heat transfer through the movement of fluids (liquids or gases), like in boiling water.
• Radiation: Heat transfer through electromagnetic waves, like heat from the sun.

c. Laws of Thermodynamics

These laws govern the behavior of energy and its transformations.

4. Light (Optics)

Optics is the branch of physics that studies the behavior and properties of light, including its interactions with matter and the construction of instruments that use or detect it.

a. Reflection and Refraction

• Reflection: The bouncing back of light when it strikes a surface. Angle of incidence equals angle of reflection.
• Refraction: The bending of light as it passes from one medium to another (e.g., from air to water), due to a change in speed.

b. Lenses and Mirrors

Mirrors form images by reflection, while lenses form images by refraction. Both can be plane, concave, or convex, producing different types of images (real/virtual, inverted/erect, magnified/diminished).

c. Dispersion

The splitting of white light into its constituent colors when it passes through a prism, as different colors (wavelengths) bend at slightly different angles. This is how rainbows form.

5. Electricity and Magnetism

This field explores the relationship between electric charges, currents, fields, and magnetic fields.

a. Electric Current and Ohm's Law

• Electric Current: The flow of electric charge. Measured in Amperes (A).
• Voltage (Potential Difference): The electrical potential energy difference between two points. Measured in Volts (V).
• Resistance: Opposition to the flow of current. Measured in Ohms (Ω).
• Ohm's Law: V = IR (Voltage = Current × Resistance).

b. Circuits

Components connected to form a path for electric current. Types include series and parallel circuits.

c. Magnetism

Magnets have north and south poles. Like poles repel, and opposite poles attract. Moving electric charges create magnetic fields, and changing magnetic fields can induce electric currents (electromagnetic induction).

6. Modern Physics (Brief Overview)

Includes concepts like atomic structure, radioactivity, and relativity, which are often covered at a more advanced level but have fundamental implications.

Chemistry: Fundamentals

Chemistry is the scientific discipline involved with compounds composed of atoms, i.e. elements, and molecules, i.e. combinations of atoms: their composition, structure, properties, behavior and the changes they undergo during a reaction with other compounds.

1. Atomic Structure

The atom is the basic unit of a chemical element. It consists of a nucleus (containing protons and neutrons) and electrons orbiting the nucleus.

• Proton: Positively charged particle (charge +1, mass approx. 1 amu).
• Neutron: Neutral particle (charge 0, mass approx. 1 amu).
• Electron: Negatively charged particle (charge -1, mass negligible).

Atomic Number (Z): The number of protons in the nucleus of an atom. It defines the element.

Mass Number (A): The total number of protons and neutrons in the nucleus. A = Z + N (where N is the number of neutrons).

Isotopes: Atoms of the same element with the same number of protons but different numbers of neutrons (e.g., Carbon-12 and Carbon-14).

2. Chemical Bonding

Atoms combine to form molecules or compounds through chemical bonds, which involve the sharing or transfer of electrons.

• Ionic Bond: Formed by the transfer of electrons between atoms, typically between a metal and a non-metal, forming ions (e.g., NaCl - Sodium Chloride).
• Covalent Bond: Formed by the sharing of electrons between atoms, typically between non-metals (e.g., H₂O - Water, O₂ - Oxygen gas).
• Metallic Bond: Found in metals, where electrons are delocalized and form a "sea" around positive metal ions.

3. Periodic Table of Elements

The periodic table organizes elements based on their atomic number, electron configuration, and recurring chemical properties. It is arranged in periods (rows) and groups (columns).

• Groups: Elements in the same group have similar valence electron configurations and thus similar chemical properties.
• Periods: Elements in the same period have the same highest energy level occupied by electrons.

Key groups include:

• Group 1: Alkali Metals (highly reactive)
• Group 2: Alkaline Earth Metals
• Group 17: Halogens (highly reactive non-metals)
• Group 18: Noble Gases (inert/unreactive)

4. Chemical Reactions and Equations

Chemical reactions involve the rearrangement of atoms and molecules. They are represented by chemical equations.

Example: 2H₂ + O₂ → 2H₂O (Synthesis of water)

Key types of reactions:

• Combination/Synthesis: A + B → AB
• Decomposition: AB → A + B
• Displacement: A + BC → AC + B
• Double Displacement: AB + CD → AD + CB
• Redox (Oxidation-Reduction): Involve the transfer of electrons.

Balancing Chemical Equations: The number of atoms of each element must be the same on both sides of the equation, following the Law of Conservation of Mass.

5. Acids, Bases, and Salts

• Acids: Substances that release hydrogen ions (H⁺) in water. They typically taste sour and turn blue litmus red. (e.g., HCl, H₂SO₄).
• Bases: Substances that release hydroxide ions (OH^-) in water or accept H⁺ ions. They typically taste bitter and feel slippery, turning red litmus blue. (e.g., NaOH, Ca(OH)₂).
• pH Scale: Measures the acidity or alkalinity of a solution. pH < 7 is acidic, pH = 7 is neutral, pH > 7 is alkaline (basic).
• Salts: Ionic compounds formed when an acid reacts with a base (neutralization reaction). (e.g., NaCl, formed from HCl + NaOH).

6. Water

Water (H₂O) is a vital compound with unique properties.

• It is a universal solvent.
• It exhibits high specific heat capacity, moderating temperatures.
• It shows anomalous expansion (ice is less dense than liquid water).
• Hard Water: Contains dissolved mineral ions, primarily calcium (Ca²⁺) and magnesium (Mg²⁺). Soft water lacks these.

7. Carbon and its Compounds

Carbon is the basis of organic chemistry. Its ability to form four covalent bonds and chain with itself leads to a vast array of compounds.

• Allotropes: Different structural forms of the same element (e.g., Diamond, Graphite, Fullerenes for Carbon).
• Organic Compounds: Primarily contain carbon and hydrogen, often with oxygen, nitrogen, etc.

8. Fuels

Substances that produce heat and light when burned (combustion).

• Fossil Fuels: Coal, petroleum, natural gas (formed over millions of years from organic matter).
• Renewable Fuels: Biomass, biofuels.

9. Metallurgy

The science and technology of extracting metals from their ores and purifying them.

• Ores: Naturally occurring rocks or minerals from which a metal can be economically extracted.
• Alloys: Mixtures of a metal with one or more other elements to improve its properties (e.g., Steel = Iron + Carbon, Brass = Copper + Zinc).

Biology: Fundamentals

Biology is the scientific study of life. It explores the structure, function, growth, origin, evolution, and distribution of living organisms.

1. The Cell: Basic Unit of Life

The cell is the smallest structural and functional unit of all known living organisms.

• Cell Theory:
  • All living organisms are composed of one or more cells.
  • The cell is the basic unit of structure and function in all living organisms.
  • All cells arise from pre-existing cells.
• Prokaryotic Cells: Simpler cells lacking a membrane-bound nucleus and organelles (e.g., Bacteria).
• Eukaryotic Cells: More complex cells with a membrane-bound nucleus and organelles (e.g., Plant cells, Animal cells, Fungi).

Key Organelles in Eukaryotic Cells:

• Nucleus: Contains genetic material (DNA).
• Mitochondria: Powerhouse of the cell, site of cellular respiration.
• Chloroplasts: Site of photosynthesis (in plant cells and some algae).
• Ribosomes: Protein synthesis.
• Endoplasmic Reticulum (ER): Involved in protein and lipid synthesis.
• Golgi Apparatus: Modifies, sorts, and packages proteins and lipids.
• Lysosomes: Contain digestive enzymes.
• Vacuoles: Storage (larger in plant cells).
• Cell Membrane: Regulates passage of substances into and out of the cell.
• Cell Wall: Provides structural support and protection (in plant cells, fungi, bacteria).

2. Cell Division

The process by which a parent cell divides into two or more daughter cells.

• Mitosis: Produces two genetically identical diploid daughter cells. Essential for growth and repair.
• Meiosis: Produces four genetically unique haploid daughter cells (gametes). Essential for sexual reproduction.

3. Genetics: The Study of Heredity

Genetics is the study of genes, genetic variation, and heredity in organisms.

• DNA (Deoxyribonucleic Acid): The molecule that carries genetic instructions. It has a double helix structure.
• Genes: Segments of DNA that code for specific traits.
• Chromosomes: Structures within cells that contain DNA. Humans have 23 pairs (46 total).
• Heredity: The passing of traits from parents to offspring.

4. Metabolism: Life Processes

Metabolism encompasses all the chemical processes that occur within a living organism to maintain life.

• Photosynthesis: The process used by plants, algae, and cyanobacteria to convert light energy into chemical energy (glucose), using carbon dioxide and water, releasing oxygen.

  Equation: 6CO₂ + 6H₂O + Light Energy → C₆H₁₂O₆ + 6O₂

• Respiration: The process by which organisms break down glucose to release energy (ATP).
  • Aerobic Respiration: Occurs in the presence of oxygen. C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + ATP (Energy).
  • Anaerobic Respiration: Occurs in the absence of oxygen (e.g., fermentation).

5. Classification of Living Organisms

Biologists classify organisms into hierarchical groups based on shared characteristics.

The main taxonomic ranks (from broadest to most specific): Kingdom, Phylum, Class, Order, Family, Genus, Species.

The five-kingdom system (proposed by Whittaker) is common:

• Monera: Prokaryotes (e.g., Bacteria, Cyanobacteria).
• Protista: Unicellular eukaryotes (e.g., Amoeba, Paramecium, Algae).
• Fungi: Heterotrophic eukaryotes, often decomposers (e.g., Yeast, Mushrooms).
• Plantae: Multicellular autotrophs (plants).
• Animalia: Multicellular heterotrophs (animals).

6. Human Body Systems

The human body is organized into complex systems that work together.

• Digestive System: Breaks down food and absorbs nutrients.
• Circulatory System: Transports blood, oxygen, nutrients, and waste products (Heart, Blood Vessels).
• Respiratory System: Facilitates gas exchange (Lungs).
• Nervous System: Controls and coordinates body activities (Brain, Spinal Cord, Nerves).
• Skeletal System: Provides support and protection (Bones).
• Muscular System: Enables movement.
• Excretory System: Removes waste products (Kidneys).
• Endocrine System: Produces hormones that regulate body functions.
• Reproductive System: For reproduction.

7. Health and Diseases

Understanding common diseases, their causes (pathogens like bacteria, viruses, fungi), modes of transmission, and prevention is important.

• Communicable Diseases: Can be spread from person to person (e.g., Common cold, Tuberculosis, Malaria).
• Non-Communicable Diseases: Cannot be spread (e.g., Heart disease, Diabetes, Cancer).
• Vaccination: A method of stimulating the immune system to provide immunity against a specific infectious disease.

8. Ecosystems and Environment

An ecosystem includes all the living organisms (biotic factors) in an area, as well as the non-living physical components (abiotic factors) like air, water, and soil. Concepts like food chains, food webs, and the flow of energy are key.