Science I - General Science Pointers

General Science Pointers

Basic Concepts and Laws

Science and Technology

• Science: Systematic study of facts, principles, and methods observed in natural, physical, and social environments.
  • Derived from the Latin word 'scire,' meaning 'to know.'
  • It is both a body of knowledge and a problem-solving process.

Branches of Science

The Physical Sciences

• Physics: Study of matter, energy, and their interactions.
  • Includes subjects like gravity, light, and time.
  • Albert Einstein developed the Theory of Relativity.
• Chemistry: Science dealing with the composition, properties, reactions, and structure of matter.
  • Louis Pasteur discovered pasteurization.
• Astronomy: The study of the universe beyond Earth's atmosphere.

The Earth Sciences

• Geology: Science of the origin, history, and structure of the Earth.
• Oceanography: Exploration and study of the ocean.
• Paleontology: Science of prehistoric life forms.
• Meteorology: Science dealing with the atmosphere, weather, and climate.

The Life Sciences (Biology)

• Botany: The study of plants.
• Zoology: Science covering animals and animal life.
• Genetics: The study of heredity.
• Medicine: Science of diagnosing, treating, and preventing illness, disease, and injury.

Scientific Method

• Logical method used by scientists to acquire knowledge and explain natural phenomena.
  • Phenomenon: A thing observed by the senses.
  • Fact: A scientifically tested observation.
• Six basic steps:
  • a. Identify and Clearly State the Problem:
    • Questions arise from unusual observations.
    • Identify a specific, measurable, and attainable problem.
  • b. Gather Information Pertinent to the Problem:
    • Recall past experiences, interview knowledgeable people, and research in libraries and research centers.
  • c. Formulate Hypothesis:
    • Make an educated guess based on gathered information or data.
  • d. Test the Hypothesis:
    • Carry out experiments.
      • Controlled experiment: Manipulating one condition or factor that may affect the result.
        • 1) Trials: Number of times an experiment is repeated.
        • 2) Controls: Factors kept constant.
        • 3) Variables: Factors that change.
          • Kinds:
            • 1. Independent or experimental: Factors that are changed.
            • 2. Dependent: Factors that change as a result of changes in the independent variable.
  • Presentation of Data
    • Tables
      • Easy to read, organized presentations.
    • Graphs
      • Readily show patterns of data.
        • Kinds:
          • 1. Line Graph: Comparing two continuously changing variables.
          • 2. Bar Graph: Comparing a changing value with an unchanging value.
  • e. Draw a Generalization or Conclusion:
    • Conclusion: A statement about the result of the experiment.
    • Law: Describes what happens but does not explain why.
    • Theory: Hypothesis explained from observations.
  • f. Apply the Principle (Conclusion) to Other Situations.

Scientific Traits

• Knowledge obtained through models, ideas, serendipity, or accidental discovery.
• Standards or procedures must be observed.
• Scientists should exhibit:
  • a. Curiosity: Keen observation of surroundings. Example: Galileo's study of heavenly bodies.
  • b. Logic and System: Use of step-by-step experimental method and keeping accurate records. Example: Gregor Mendel's study of hereditary traits.
  • c. Open-mindedness: Willingness to change ideas when necessary. Example: Johannes Kepler's shift from circular to elliptical orbits.
  • d. Intellectually Honest: Acknowledging contributions of others. Example: Isaac Newton recognizing Galileo's role in Laws of Motion.
  • e. Hard work and perseverance: Example: Marie and Pierre Curie's work on uranium ore.
  • f. Not Opinionated: Using evidence to prove theories. Example: John Dalton's atomic theory.
  • g. Creativity and critical thinking: Example: Albert Einstein developing his own theory in different perspective.

Technology

• Application of scientific knowledge to practical purposes (applied science).
• Classified into:
  • a. Machines: Tools that aid and accelerate activities. Examples: airplanes, internet, CT scans, computers.
  • b. Products: Materials produced artificially or naturally for convenience and comfort. Examples: steel, toothpaste, fertilizers, pesticides.
  • c. Processes: Ways of doing things. Examples: food preservation, prawn culture, induced fruiting.

Measurement

International System (SI) of Measurement

• Comparing a quantity with a chosen standard, agreed upon by scientists and legally enforced globally.
• Seven basic quantities:
  • Length: Meters (m)
  • Mass: Kilograms (kg)
  • Time: Seconds (s)
  • Electric current: Amperes (amp)
  • Temperature: Kelvin (K)
  • Amount of substance: Moles
  • Luminous intensity / light: Candelas
• Accuracy affected by:
  • Proper use of measuring instruments.
  • Precision of the instrument.
• Unit factor method: Canceling undesired units using fixed relationships.

Metric Prefixes

• Powers of 10, handy for metric conversions.
• Prefixes, symbols, and factors:
  • giga (G): 10^9 = 1,000,000,000
  • mega (M): 10^6 = 1,000,000
  • kilo (k): 10^3 = 1,000
  • hecto (h): 10^2 = 100
  • deka (da): 10^1 = 10
  • deci (d): 10^{-1} = 0.1
  • centi (c): 10^{-2} = 0.01
  • milli (m): 10^{-3} = 0.001
  • micro (µ): 10^{-6} = 0.000,001
  • nano (n): 10^{-9} = 0.000,000,001
  • pico (p): 10^{-12} = 0,000,000,000,001

Temperature

• Three scales: Fahrenheit, Celsius, and Kelvin.
• Fahrenheit:
  • Freezing point of water: 32°F
  • Boiling point of water: 212°F
  • Conversion formula: F = (9/5)C + 32
• Celsius (Centigrade):
  • Freezing point of water: 0°C
  • Boiling point of water: 100°C
  • Conversion formula: C = (5/9)(F - 32)
• Kelvin:
  • Base unit of thermodynamic temperature in SI.
  • Defined as 1/273.16 of the triple point of pure water.
  • Conversion formula: K = C + 273

Volume

• Amount of space an object occupies.

Volume of a Regular Solid

• Having length, width, and thickness measurable in a straight line.
• Measured in cubic units.

Volume of a Liquid

• Measured in cubic meters or liters (L).
• Graduated cylinder used to measure the volume.
• Read the lower meniscus for clear liquids and the upper meniscus for colored liquids.

Volume of an Irregular Solid

• Dimension cannot be measured in a straight line.
• Displacement method is used to determine the volume.

Displacement Method

• Fill a container with water, submerge the object, and catch the overflow; the volume of overflow equals the volume of the object.
• Example: Calculating the volume of a block of wood with L = 2 cm, W = 2 cm, and T = 2 cm.
  • Volume = L
    vW
    T = 2
    2
    2 = 8 cm^3

Liquid Volume Equivalents

• 1 dm^3 = 1 L
• 1 cm^3 = 1 mL
• 1000 cm^3 = 1 L

Density

• Mass per unit volume: D = M/V
• Materials with density less than 1 g/cc float on water; those greater than 1 g/cc sink.
• Example: Object with volume 1.4 cc and mass 2.5 g.
  • D = 2.5 g / 1.4 cc = 1.79 g/cc
  • The object will sink because its density is greater than that of water (1 g/cc).

Force

• Measurement of a push or a pull.
• Changes speed and direction of moving objects or initiates movement of stationary objects.

Measuring Force

• Gravitational force is measured by the weight of an object.
• Instruments: Bathroom scale and balance (kilohan).

Types of Forces

• Gravitational force: Downward force exerted by the Earth.
• Inertia: Tendency of an object to remain at rest or maintain its motion.
• Friction: Resists the sliding movement of two surfaces in contact.
• Centripetal force: Drives an object toward a center of rotation, keeping it in a circular path.
• Force of Gravity: Enables an object to exert an equal and opposite force on its support.
• Nuclear Force: Strongest known force, holding together protons and neutrons in the nucleus.
• Electromagnetic Force: Binds electrons to the nucleus, atoms in molecules, and ions in solid matter.

Mass vs Weight

• Mass: Quantity of matter, constant, measured in kilograms.
• Weight: Measure of the pull of gravity on an object, depends on mass and distance from the Earth's center, expressed in Newtons (N).
• 100 g = 1 N

Work

• Force applied to an object that moves it in the direction of the force: Work = Force
  Displacement

Calculating the Amount of Work

• W = F
  d (Newton-meter or joule)
• Example: Pushing a sack of rice with a force of 50 N across a distance of 10 meters.
  • W = 50 N
    10 m = 500 Nm = 500 J

Machines

• Mechanical device used to aid in doing work.
  • Simple Machines have one or two parts.
  • Compound Machines use two or more simple machines.

Simple Machines

• a. Lever: Rigid body pivoting around a fulcrum. Examples: crowbar, hammer, pliers.
• b. Pulley: A wheel with a grooved rim over which a rope passes. Example: flagpole.
• c. Wheel and Axle: Wheel attached to an axle, turning together. Examples: doorknob, eggbeater, screwdriver.
• d. Inclined Plane: Flat surface with one end higher than the other. Example: plank, ladder, winding road.
• e. Wedge: Inclined plane with one or two sloping sides. Examples: nail, scissors, chisel, knife.
• f. Screw: Spiral inclined plane. Example: food grinder, metal screws.

Energy

• Derived from the Greek word 'energeial' (en = in, ergon = work).
• The ability to do work or exert force to move an object.

Forms of Energy

• a. Mechanical Energy
  • Kinetic energy: Energy of motion.
  • Potential energy: Energy of position or state.
• b. Internal Energy or Thermal Energy: Total energy from attractive and repulsive forces of particles in a body.
• c. Heat Energy: Energy flowing from one body to another due to temperature difference.
• d. Electrical Energy: Energy of electrons flowing through conductors.
• e. Chemical Energy: Energy stored in matter due to attraction forces and arrangement of subatomic particles.
• f. Radiant Energy: Energy of electromagnetic waves (radio waves, infrared rays, visible light, ultraviolet rays, x-rays, gamma rays).
• g. Nuclear Energy: Energy released from nuclear fusion or fission of atomic nuclei.

Methods of Heat Transfer

• Conduction: Heat transfer through molecular collisions in a material.
• Convection: Heat transfer by the movement of a gas or liquid due to temperature differences.
• Radiation: Heat transfer through emission of energy in all directions.

Energy Resources

• a. Fossil Fuels
  • Coal: Formed from trees and vegetation buried in swamps.
  • Petroleum: A liquid mixture of gaseous, liquid, and solid hydrocarbons.
  • Natural Gas: Composed of carbon and hydrogen (50-94% methane).
• b. Hydroelectric Power: Electricity generated by water turbines.
• c. Geothermal Energy: Thermal energy from beneath the Earth's surface.
• d. Wind Energy: Energy harnessed through windmills.
• e. Solar Energy: Radiant energy from the sun harnessed using solar cells or photovoltaic cells.

Earth

Formation of the Earth

• Big Bang Theory: Initially, a super-massive gaseous point exploded, creating protons, neutrons, and electrons.
• Particles cooled and combined to form hydrogen and other atoms.
• Gravity pulled atoms together to form gaseous bodies, which collapsed and initiated fusion, creating stars.
• After fusion ended, stars exploded, distributing matter that combined to form planets and other celestial bodies.

Formation of the Solar System

• A star formed where the Sun is now located and exploded, sending matter in all directions.
• Gravity caused the matter to cool and collect, forming planets and the asteroid belt.
• A smaller star formed at the center, becoming the Sun and restarting the fusion process.

Earth’s Structure

• The Earth consists of the core, mantle, and crust, surrounded by the atmosphere.
• Seismology is used to research the Earth's materials, layers, and their effects on the surface.

The Core

• Inner part of the Earth, about 1,800 miles (2,900 km) below the surface.
• Dense ball of iron and nickel, divided into the inner and outer core.
• Inner core: Solid, 780 miles (1,250 km) thick, temperature reaches 6700°F (3700ºC).
• Outer core: Molten, 1370 miles (2,200 km) thick, spins around the inner core due to Earth's rotation, causing Earth's magnetism.

The Mantle

• Layer above the core, starts 6 miles (10 km) below the oceanic crust and 19 miles (30 km) below the continental crust.
• Divided into the inner and outer mantle, 1,800 miles (2,900 km) thick, makes up 80% of Earth's volume.

The Crust

• Hard outer shell, surface on which we live.
• Thinner than the other layers, floats on the denser mantle.
• Oceanic crust: 4-7 miles (6-11 km) thick, made of heavy rocks like basalt.
• Continental crust: 19 miles (30 km) thick, made of light material like granite.

Plate Tectonics

• Earth's crust consists of moving plates that collide or pull apart.
• The lithosphere consists of large and small plates.
• Plate tectonics explains continental drift, seafloor spreading, volcanic eruptions, and mountain formation.
• The movement may be caused by the slow churning of the mantle.

Continental Drift

• Plates drift, changing the Earth's appearance over millions of years.
• The east coast of North and South America fits into the west coast of Europe and Africa.

Diverging Plates

• Plates pull apart, hot magma emerges as lava, forming new oceanic plates.
• Occurs at mid-ocean ridges, areas of volcanic and earthquake activity.
• Example: Mid-Atlantic Ridge.

Converging Plates

• Plates move together, edges can be destroyed by collision or crimped to form mountain ranges.
• Subduction: One tectonic plate bends beneath the other, often an oceanic plate colliding with a continental plate.
• Ocean trenches and island arcs are formed.

Seafloor Spreading

• Volcanic activity causes magma to rise, forming a ridge along the middle of oceans.
• When continental plates collide, one plate splits into two layers; the mantle layer subducts, and the upper layer crumples up forming mountain ranges.
• Crumpled mountains are formed by the collision of continental plates.

Diastrophism

• Movements of the Earth's crust that push a portion up, down, or sideways.
• Folding: Sideward forces deform rocks into wavelike folds.
• Faulting: Sliding or moving of rock layers along a break or fracture.

Volcanoes

• A gap in Earth where molten rock and other materials reach the surface.
• Magma: Molten rock that occurs by partial melting of the crust and mantle.
• Lava: Magma that comes to the Earth's surface.

Active and Non-Active Volcanoes

• Active volcanoes: Likely to erupt.
• Dormant volcanoes: Lie dormant for centuries, then erupt suddenly.
• Extinct volcanoes: No longer likely to erupt.

Types of Volcanoes

• Shield volcano: Broad, shallow volcanic cone.
• Dome volcano: Steep, convex slope from fast-cooling lava.
• Ash-cinder volcano: Alternating layers of ash and cinder.
• Composite volcano: Alternating layers of lava and ash with many craters.
• Caldera volcano: Large crater with new craters forming inside.

Earthquakes

• Shaking of the ground caused by sudden movements in the Earth's crust.
• Caused by movement of tectonic plates.
• Seismic waves: Vibrations caused by cracking of rocks that cause an earthquake.
• Focus (hypocenter): Source of the earthquake.
• Earthquakes are classified by the depth of the focus:
  • Shallow earthquakes: 0-43 miles (0-70 km) below ground.
  • Intermediate earthquakes: 43-186 miles (70-300 km) below ground.
  • Deep earthquakes: Deeper than 186 miles (300 km) below ground.

Earthquake Intensity

• The closer the focus is to the surface, the heavier the earthquake.
• Epicenter: The surface directly above the focus.
• Foreshocks: Light vibrations before the main shock.
• Aftershocks: Minor shocks that occur afterward as rocks settle down.

Rocks

• Classified into three types based on formation.

Types of Rocks

• a. Igneous rocks: Formed from cooled and solidified molten rock (magma).
  • Intrusive igneous rocks: Solidify beneath Earth's surface (e.g., Granite).
  • Extrusive igneous rocks: Solidify at the surface (e.g., Basalt, obsidian).
• b. Sedimentary rocks: Formed when sediment gets packed together over millions of years (e.g., Limestone, sandstone, shale).
• c. Metamorphic rocks: Sedimentary or igneous rocks transformed by heat, pressure, or both (e.g., Schist, marble, slate).

The Rock Cycle

• Interrelation of the three major types through natural processes.
• Igneous to Sedimentary: Weathering and erosion form sediments, turning into sedimentary rocks through compaction and cementation.
• Sedimentary to Metamorphic: Burialsubjects rocks to heat and pressure.
• Metamorphic to Igneous: Complete melting leads to magma.
• Additional complexities include: (1) weathering of sedimentary and metamorphic rocks and (2) metamorphism of igneous rocks and repeated metamorphism of metamorphic rocks.

Weathering

• Breaking down rocks physically or chemically, giving rise to sediments or rock fragments.

Types of Weathering

• A. Physical or mechanical weathering
  • Frost wedging: Water expands when it freezes.
  • Exfoliation or unloading: Rock breaks off into sheets due to expansion.
  • Thermal expansion: Repeated heating and cooling causes stress.
• B. Chemical weathering
  • Rock reacts with water, gases, and solutions, adding or removing elements.
  • Dissolution (or solution): Minerals dissolve in water (e.g., halite, calcite).
  • Oxidation: Oxygen combines with iron-bearing minerals, causing