energy transfers

• Energy stored in the movement of particles is known as internal energy, also known as heat/thermal energy.
• Internal energy - total energy stored in a substance. Measured by Joules (J).
• Internal energy is potential energy + kinetic energy
• Internal energy can also be measured in calories.
• Internal energy depends on the substance and the state of the substance (solid, liquid, gas, etc.)
• Internal energy changes when heat is added or removed or when work is done on or by the substance
• Temperature is kinetic energy, the hotness or coldness of a substance. It is measured in Celsius, Fahrenheit, or Kelvin.
• Temperature depends on how fast the particles are moving.
• Temperature changes when heat is added or removed.
• Amount of internal energy depends on the following:

  -Temperature

  -Mass

  -Material
• Energy is transferred when there is a temperature difference. Hotter object gives out energy to colder objects, and the different in temperature reduces until it reaches thermal equilibrium.
• The bigger the difference in temperature, the faster the energy is transferred.
• A liquid evaporates fastest at its boiling point, but it can evaporate at any temperature.
• Evaporation can transfer energy. The fastest moving particles in a liquid evaporates first and forms a gas, bringing the kinetic energy with them. The rest of the particles left has less kinetic energy, leaving it cooler than it was before.
• Energy can be transferred through conduction, convection, and radiation.
• Radiation (infrared radiation) - all objects transfer energy to their surroundings via infrared radiation. Hotter objects gives out more infrared radiation.
• In radiation, when the heat hits something, it can be absorbed, or it can be reflected.
• Radiation does not need any medium to travel through, and it can travel through transparent substances like air and glass
• Thermal imagers are instruments measuring infrared radiation and convert the data into temperature maps.
• Conduction: thermal energy is transferred through solid materials. The particles vibrate and transfer energy to neighbouring particles.
• Energy that can travel easily through sold materials are likely to be thermal conductors. On the other hand, substances that cannot absorb heat well are known as heat insulators.
• Conduction happens best with solids as the particles are very close together.
• Convection: energy is transferred through fluids.
• Convection causes the rising and falling of liquids and gases due to differences in density caused by temperature differences.
• In convection, the heated particles expand and become less dense, going above the colder particles. This is known as convection currents.
• White colored clothes absorb less heat that dark colored clothes. Shiny colors reflect the heat off.