Energy, Heat, and Temperature: Understanding the Basics
Energy
Energy is a physical quantity that represents the capacity of bodies to cause transformations in themselves or in other bodies.
Types of Energy
- Mechanical Energy: Possessed by bodies in motion (kinetic energy), those at a certain height (potential energy), or those that have experienced deformation (elastic energy).
- Electrical Energy: Possessed by electric current.
- Nuclear Energy: Produced in nuclear reactions of fusion and fission.
- Thermal Energy: Energy that flows from one body to another when there is a temperature difference between them.
- Chemical Energy: Possessed by substances in nature, energy due to their bonds.
- Radiant Energy: Possessed by electromagnetic radiation.
Non-Renewable Energy Sources
- Coal: Sedimentary rock used as fuel in industries and metallurgical thermal power plants.
- Petroleum: Currently, most energy is obtained from it.
- Natural Gas: Has great heating power, is clean, and low-polluting.
- Fissionable and Fusionable Materials: Reactions in nuclear fusion and fission produce a lot of energy.
Renewable Energy Sources
- Reservoir Water: Water retained at high altitudes possesses potential gravitational energy that can be converted into kinetic and then electrical energy.
- Wind: In wind farms, the energy of the wind is transmitted by wind turbines to an electric generator.
- Sun: Its electromagnetic radiation is absorbed by plates used in homes for heating or obtaining electricity.
- Sea Water: Tidal and wave power plants use the motion of the water to produce electricity.
- Biomass: Non-fossilized organic matter is used directly as fuel.
- Internal Land Heat: Thermal springs, geysers, or fumaroles are manifestations of geothermal energy.
Work
The work of a constant force whose point of application moves on a rectilinear path is equal to the scalar product.
Joule
The work done when a force of 1 Newton displaces its point of application 1 meter in the same direction and sense of the force.
Resultant Force
It is equal to the sum of the work done by each of the forces acting on a body.
Kinetic Energy
The capacity of a body to do work due to being in motion.
Gravitational Potential Energy
The energy possessed by bodies due to being at some distance above the Earth’s surface.
Mechanical Energy
The sum of its kinetic energy and potential energy.
Effects of Heat
- Temperature Increase: Appreciated with a thermometer.
- Change of Aggregation State: For example, the step from solid to liquid.
- Body Dilation: We notice an increase in its size.
Specific Heat
The heat that a unit of mass of a substance must receive to increase its temperature by 1 Kelvin.
Internal Energy
The total energy of the constituent particles, that is, the sum of all the energy possessed by the particles: atoms, molecules, and ions.
Molecular Kinetic Theory
The particles of bodies are constantly moving with variable velocities. This movement is called thermal agitation, and they possess kinetic energy. A body has greater thermal agitation if its particles move at high speed.
Temperature of Bodies
It is a measure of the average kinetic energy of the particles, so that a body has a higher temperature than another if the average kinetic energy of its particles is greater.
Thermometers
Instruments used to measure the temperature of bodies and are characterized by: – Quickly reaching the temperature of the body they are in contact with. – Measuring the temperature indirectly.
Temperature Scales
- Celsius: Assigns a value of 0°C to the normal melting point of water and 100°C to the boiling point of water.
- Kelvin: The normal melting point of water is 273 K, and the boiling point is 373 K.
- Fahrenheit: The normal melting point of water is 32°F, and the boiling point is 212°F.
Forms of Heat Transfer
- Conduction: Heat transfer occurs by transmission of energy from one particle to another without displacement.
- Convection: Heat transfer occurs through the movement of particles in a fluid.
- Radiation: Heat transfer occurs through electromagnetic waves without the intervention of material particles that transmit it.
Molecular Kinetic Theory
Provides an explanation of the changes of state:
- Heat Absorption: Produces an increase in the kinetic and potential energy of the body’s particles. If the existing attractive forces between them are overcome, it goes from solid to liquid or liquid to gas.
- Heat Release: Involves a decrease in the kinetic and potential energy of the particles. This decrease results in an increase in the attractions between them, so that gas can pass to liquid and liquid to solid.