Sample Work:
Question 1: Explain the difference between thermal energy and temperature.
Answer:
Thermal energy refers to the total internal energy of an object due to the random motion of its atoms and molecules. It is the sum of the kinetic energy and potential energy of all the particles within an object. Thermal energy depends on the mass, temperature, and specific heat capacity of the object.
Temperature, on the other hand, is a measure of the average kinetic energy of the particles within an object. It is a scalar quantity that is measured in units such as degrees Celsius or Fahrenheit. Temperature does not depend on the size or the number of particles in an object but rather the kinetic energy of the particles.
In simpler terms, thermal energy is the total energy of all the particles in an object, while temperature is a measure of how hot or cold the object is based on the average kinetic energy of the particles.
Question 2: Describe three ways to transfer thermal energy.
Answer:
There are three main ways in which thermal energy can be transferred:
1. Conduction: Conduction is the transfer of thermal energy through direct contact between particles. In solids, the particles are closely packed, allowing energy to be passed from one particle to another through collisions. Good conductors, such as metals, allow thermal energy to pass quickly, while poor conductors, such as insulators, slow down the transfer of energy.
2. Convection: Convection is the transfer of thermal energy through the movement of a fluid, either liquid or gas. When a fluid is heated, it becomes less dense and rises, while the colder, denser fluid sinks. This creates a circular motion called a convection current, which transfers energy from one part of the fluid to another.
3. Radiation: Radiation is the transfer of thermal energy through electromagnetic waves. Unlike conduction and convection, radiation can occur in a vacuum, as it does not require a medium. Heat energy is radiated as electromagnetic waves, such as infrared radiation, which can be absorbed by other objects, converting the radiation into thermal energy.
Question 3: Explain how insulation works and give an example.
Answer:
Insulation is a material that reduces or prevents the transfer of thermal energy between objects of different temperatures. It works by slowing down the flow of thermal energy through conduction, convection, or radiation.
For example, a common form of insulation used in homes is fiberglass. Fiberglass insulation consists of fine glass fibers that trap pockets of air. Air is a poor conductor of heat, so the air trapped in the fiberglass helps to slow down the transfer of thermal energy through conduction. Additionally, the fibers themselves are good at reflecting and absorbing radiation, further reducing the transfer of energy. This helps to keep the warm air inside the house during the winter and to keep the hot air out during the summer, making the house more energy-efficient and comfortable.
Overall, insulation works by reducing the amount of thermal energy that can be transferred between objects, helping to maintain a more stable and desired temperature.
Thermal Energy Sample Work Science 8 Q1 / Thermal Energy portfolio
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