• Heat in J (joules) - Total energy of a system
• Temperature (T) - Degree of energy in a system
• Heat depends on Mass and Temperature

Heat Transfer

• Heat always moves from hotter place to cooler place
• Hot objects in a cool room will cool down to room temperature whereas cool objects in a hot room will warm up(Heat) to room temperature

Heat transfer methodology

• Conduction - Solids
  • Happens through vibration of particles
• Convection - Fluids (Liquids and Gases)
  • Happens through transfer of particles
• Radiation - Doesn’t require a medium (can happen in space)
  • a process where heat waves are emitted that may be absorbed, reflected, or transmitted through a colder body

Conduction

• When you heat a metal strip, the heat travels to the other end
  • The kinetic energy of the particles increases as heat energy is supplied to them, this causes an increase in the vibrational energy of the particles. As the vibrational energy increases, the number of vibrating particles increases as the heat energy is transferred for one particle to its neighbouring particles.
    • This process continues until the KE has passed onto all of the particles in the metal strip, effectively heating the strip from one end all the way until the other one.
    • Note: Heat is traveling through the particles, the particles aren’t moving but the heat is, all the particles are doing is vibrating
• Conduction requires direct contact to make the heat transfer, so the above example of the metal strip is the phenomenon of conduction

Simplified way of saying the above:

• When the metal is heated, electrons gain KE causing them to vibrate and spread the KE to the neighboring particles causing the transfer of heat throughout the medium.

Convection

• Convection is the process of heat transfer in fluids by the actual motion of matter.
• It happens in liquids and gases (fluids)
• When a fluid is heated from below, thermal expansion takes place. The lower layers of the fluid, which are hotter, become less dense. We know that colder fluid is denser. Due to buoyancy , the less dense, hotter part of the fluid rises up. And the colder, denser fluid replaces it. This process is repeated when this part also gets heated and rises up to be replaced by the colder upper layer. This is how the heat is transferred through convection.
• No convection in metals are they have rigid bonds (unless aq)