sci a terms

• Heat


  This is a form of energy and is also known as thermal energy.
• - Temperature (average molecular kinetic energy)

  - Phase (change in body's internal energy) in isolated system


  Heat transfer may change an object's: (2)
• Internal energy of a substance


  The sum of molecular kinetic energy, the molecular potential energy, and other kinds of molecular energy.
• Sir Benjamin Thompson


  He immersed the hot cannon in a container of water and saw the water near the cannon was boiling. He suggested a relationship between the amount of heat generated and the mechanical work done.
• James Prescott Joule


  He experimentally determined the mechanical work needed to produce a given amount of heat.
• Thermodynamics


  Meaning "movement of heat." The study of heat

  and its transformation to other forms of energy (Thermal, mechanical, electrical, chemical, or radiant and vice versa)
• Heat Engines


  A device that converts heat energy to work. It can be in the form of the internal combustion engine in cars to giant turbines that generate electricity.
• Working substance


  All heat engines make use of substance inside them that undergoes cooling or heating, compression or expansion and sometimes change phase. The substance is called:
• Internal combustion engine


  Classification of heat engine. An engine where the fuel burns inside.
• External combustion engine


  Classification of heat engine. An engine where the fuel burns outside.
• Hot reservoir or heat source


  The external source of engines that supply the heat (HH).
• Cold reservoir or heat sink


  The rest of the heat (Hc) that is not used for work is placed:
• Cycle


  A series of processes that all engines follow.
• Thermal Efficiency


  This is defined as the ratio of output work to the input energy. Often stated as a percentage.
• The Human Body


  This is considered as heat engine, with food as the main source of energy. However, only 20 to 30% of the heat derived from food is converted to useful work.
• According to the 2nd Law of Thermodynamics, some waste heat is always produced and heat naturally flows from hot to cold objects.


  Why is it impossible for 100% thermal efficiency?
• The First Law of Thermodynamics


  States that part of the heat transferred to an object is used by the object to do work. The remaining heat changes the internal energy of an object.
• The Kelvin-Plank Statement for the Second Law of Thermodynamics


  States that: no heat engine can completely convert heat energy to work. There is no 100-percent efficient heat engine
• The Clausius Statement for the Second Law of Thermodynamics


  States that: Heat flows naturally from hot to cold object.
• The Entropy Statement for the Second Law of Thermodynamics


  States that: When reversible process occur, the total entropy of the universe remains the same. When irreversible process occurs, the total entropy of the universe increases.
• Entropy


  This is a thermodynamic measure of disorder.
• The Third Law of Thermodynamics

  State that it is impossible to lower the temperature to 0 Kelvin, Thus even ideal engine cannot attain 100-percent efficiency.
• Ideal heat engine or Carnot Engine


  This hypothetical heat engine was proposed by Sadi Carnot.
• Ideal Efficiency


  The efficiency of the Carnot engine is called:
• Mechanical Energy


  The energy acquired by the objects upon which work is done is known as: (The sum of KE and PE)
• Potential Energy


  Energy due to position or configuration is termed:
• Kinetic Energy


  Energy due to motion is termed:
• - Gravitational

  - Chemical

  - Elastic

  - Electrical

  - Nuclear


  The forms of potential energy (5)
• - Motion

  - Radiant

  - Sound

  - Thermal

  - Wave


  The forms of kinetic energy (5)
• Gravitational Potential Energy (GPE)


  The potential energy of the body due to its

  position
• Elastic Potential Energy (EPE)


  Compressed or stretch springs and stretched

  rubber bands exhibit another potential

  energy, namely:
• Law of Conservation of Energy


  States that: "Energy can never be created from nothing nor can it be destroyed into nothing. Energy is simply transformed from one form to another or transferred from one system to another."
• Momentum


  A property of a moving object that makes it hard to stop.
• Impulse


  The amount of change in an object's momentum.
• Impulse-Momentum Theorem


  This theorem reveals some interesting relationships such as the inverse relationship between force and time.
• Law of Conservation of Linear Momentum


  States that for a collision occurring between object A and object B in an closed system, the total momentum of the two objects before the collision is equal to the total momentum of the two objects after the collision.
• Elastic


  Type of collision that occurs when the colliding objects separate each other. Momentum and kinetic energy is conserved.
• Inelastic


  Type of collision that occurs when the colliding objects separate each other due to the difference in mass.
• Perfectly Inelastic


  Type of collision that occurs when the colliding objects become one mass. Momentum is conserved but kinetic energy is not.
• Projectile Motion


  The motion of a body projected horizontally or at angle other than 90° with the vertical