Exploring the Universe: Matter, Energy, and Change
Item 1: Matter and Energy
The universe consists of matter and energy. We need input from the field and energy to live. Matter is anything that occupies space and has mass and inertia. Energy is the ability to do work. The universe is the totality of matter and energy in constant change and evolution.
General Properties of Matter:
- Interaction: Indicates the existence of a force between two bodies, causing changes.
- Extension: Indicates the volume of a body, measured in cubic meters.
- Inertia: Indicates the mass of a body, measured in kilograms.
- Corpuscular Structure: Indicates the amount of substance of a body, measured in moles.
We expend energy to obtain food (for vital functions) and to transform matter for energy (for machines).
Change: Any observable and measurable occurrence. The causes of changes are gravitational interactions (due to mass), electromagnetic interactions (due to the electric charge of atoms), and nuclear interactions (changes in chemical elements). Change involves a transfer of energy.
Types of Changes:
- Physical: Occur without changing the nature of substances.
- Chemical: Involve changes in the substance.
- Nuclear: Involve the exchange of chemical elements.
Item 2: Physical Changes and Motion
Physical Changes:
- Thermal: Related to the continuous movement of particles within a substance (changes of state).
- Electrical: Occur when some materials are rubbed against others.
- Optical and Acoustical: Energy is transmitted without the transport of matter.
- Movement: Interactions cause changes in the state of rest or motion of bodies.
Nothing is at rest in an absolute sense. Motion is relative to the chosen frame of reference. Motion is the change in position of an object with respect to a frame of reference considered fixed. The path is the line connecting all the successive positions of a mobile object. Position is the location (x) with respect to the frame of reference.
Uniform Linear Motion:
- Distance Traveled (e) (m): The length of the path followed by the object from the initial position (Xo) to the final position (Xf).
- Time (t) (s): The time it takes for the object to travel the path.
- Speed (v) (m/s): The distance the object travels per unit of time.
Road route:
Unobstructed?
This is the general equation of uniform linear motion (indicating the final position of the mobile).
Force (newton, N): A cause capable of changing the motion, rest, or shape of bodies. Inertia is the property of matter by which it tends to maintain its state of motion. Weight is the force with which bodies are attracted to Earth. Friction is a force that occurs between moving bodies and the surfaces they contact. It is an electromagnetic force.
Difference Between Mass and Weight: Weight is measured in newtons (N) in the SI system and varies on different planets. Mass measures inertia, is measured in kilograms, and is independent of gravity.
Item 3: Thermal Changes and Chemical Changes
Thermal Physical Changes: Matter is made up of particles separated by empty space. Simpler particles are atoms, which form molecules and crystals. Molecules can coalesce to form liquids and solids or remain separate and form gases. Intermolecular attractions cause molecules to attract each other with cohesive forces, tending to form condensed states. Thermal agitation refers to the vibrations of particles. At absolute zero (0 K or -273 °C), particles are at rest.
Chemical Changes: Changes in which atoms combine to form molecules or crystals. They involve large amounts of energy exchange. Molecular substances are formed by particles with no fixed atoms. Crystalline substances consist of atoms arranged in geometric structures.
Elements: Substances formed by atoms of the same kind. They can exist as isolated atoms, molecules, or crystals.
Compounds: Substances formed by atoms of different kinds. They can be molecular, crystalline, or chemical (organic, containing carbon atoms, and inorganic, such as minerals, rocks, some gases, and water).
Item 4: Energy and Heat
Changes are always accompanied by energy changes, which occur in two ways: by heat (transfer of energy between systems at different temperatures) and by work (when forces change the motion of objects). These are forms of energy transmission.
Energy: The capacity of material systems to produce change.
Types of Energy:
- Mechanical: Due to the position (potential) or motion (kinetic) of bodies.
Kinetic Energy (Ec): 
Potential Energy (Ep): 
Internal or Thermal Energy: Energy contained within matter. Energy is measured in joules. Heat is energy in transit between two systems at different temperatures.
Heat is transferred by conduction (transmission of energy without transporting matter), convection (movement where heated matter rises, cools, and is reheated), and radiation (bodies emit and absorb energy as heat).
Temperature Scales:
- Kelvin:
- Celsius:
- Fahrenheit:
Molecular agitation is measured in kelvin and represents temperature.
Item 6: Sound and Light
Sound is generated by the vibration of bodies. Sound waves transmit the energy that produced the vibration. Sound is the propagation of vibrations through a material medium.
Sound Properties:
- Wavelength (λ): Distance between two peaks of a wave.
- Amplitude (A): Maximum height reached by the wave.
- Frequency (f): Number of oscillations per second.
- Period (T): The time for one full oscillation.
- Hertz (Hz): Unit for measuring frequency.
Qualities of Sound:
- Intensity: Depends on the energy of the vibrating source (weak or strong).
- Pitch or Frequency: Determined by the frequency (higher or lower).
- Timbre: Quality that differentiates two sounds of equal intensity and pitch but from different sources.
- Duration: The time the wave lasts.
Light travels in a straight line in all directions.
Light Properties:
- Specular Reflection: Occurs when light reflects off a polished surface, forming images.
- Diffuse Reflection: Occurs when light reflects off an irregular surface and scatters in all directions.
- Refraction: Change in direction of light when it passes from one medium to another where it travels more slowly.
- Color: How our brain interprets light of different frequencies. Colors are a creation of the brain. An object absorbs light of different frequencies, and the brain interprets the reflected light as a specific color.
- Dispersion: When light is refracted through a transparent medium, it is separated into waves of different frequencies.