Unit 3

• Describe the Kinetic Particle Model of Matter


  States that all Matter is composed of tiny particles (atoms or molecules) which are in random motion through the space that exists between them.

  • All matter is made up of many very small particles
  • The particles are in constant motion
  • No kinetic energy is lost or gained overall during collisions between particles.
  • There are forces of attraction and repulsion between the particles in a material
  • The distances between particles in a gas are large compared with the size of the particles
• Define thermal energy 


  The internal energy present in a system due to its temperature; the transfer of thermal energy when heating or cooling a substance has the symbol Q int he equation Q=M^T
• Define temperature


  The degree or intensity of heat present in a substance or object, especially as express according to a comparative scale.
• Define Kinetic energy 


  The energy resulting from the movement of an object. When associated with temperature, kinetic energy is associated with the motion of particles in a substance. (symbol Ek , unit J)
• Define specific heat capacity


  The amount of thermal energy transfer necessary to raise the temperature of one kilogram of a substance with no change in its temperature. Units J/kg/K
• Define proportionality 


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• Explain that a change in temperature is due to the addition or removal of energy of a system (no phase change)

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• Explain why the temperature of the system remains the same during the process of state change; explain it in terms of the internal energy of a system and the kinetic particle model of matter

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• Define specific latent heat

  The energy needed to change the state of a substance. It is the energy that has to be added or removed from a material in order of the material to change state. Formula: Q=mL. Units Joules.
• Define thermal equilibrium in terms of the temperature and average kinetic energy of the particles in each of the systems.

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• Explain the process in which thermal energy is transferred between two systems until thermal equilibrium is achieved, and recognise this as the zeroth law of thermodynamics.

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• Explain that a system with thermal energy has the capacity to do mechanical work.

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• Recall that the change in the internal energy of a system is equal to the energy added or removed by heating plus the work done on or by the system, and recognise this as the first law of thermodynamics and that this is a consequence of the law of conservation of energy.
• Explain that energy transfers and transformations in mechanical systems always result in some heat loss to the environment, so that the amount of useable energy is reduced

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• Define efficiency


  The ratio of useful work performed by a machine or in a process, to total energy expended or heat take in.
• Recall that electric charge can be positive or negative.
• Recall that electric current is carried by discrete electric charge carriers.
• Recall the law of conservation of electric charge

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• Recall that electric charge is conserved at all points in an electrical circuit and recognise this as Kirchhoff’s current law.
• Define electrical potential 


  The capacity of electric charge carriers to do work due to their position in an electric circuit.
• Define electrical potential difference in a circuit

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• Define power


  The rate at which work is done or the rate at which energy is transferred or transformed. Unit W.
• Explain that the energy inputs in a circuit equal the sum of energy output from loads in the circuit and recognise this as Kirchhoff’s voltage law

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• Recall that the energy available to electric charges moving in an electrical circuit is measured using electrical potential difference.
• Define resistance


  The ratio of the voltage applied to the electric current that flows through a component in an electrical circuit.
• Recall Ohm's Law. 


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• Define power dissipation over resistors in a circuit

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• Distinguish between thermal energy, temperature and kinetic energy.


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• Explain heat transfers in terms on conduction, convection and radiation


  Conduction is the process by which heat is transferred without the net movement of particles (atoms or molecules) from one area to another.

  
  

  Convection is the transfer of thermal energy within a fluid (liquid or a gas) by the movement of hot areas from one place to another, it involves the mass movement of particles within a system over a considerable distance.

  
  

  Radiation is a means of transferring heat without the movement of matter.