Basic Principle of Energy

• Energy

  -capacity or power to

  do work;

  like: to move an object
• Energy is has its quantitative

  property must be

  transferred to an

  object in order to

  perform work.
• FIRST LAW OF THERMODYNAMICS

  and LAW OF CONSERVATION

  OF ENERGY

  • Energy cannot be created nor

  destroyed.

  • Energy can be exchanged between

  objects (transfer of energy)

  • Energy is conserved and converted

  • Energy is transformed from one

  form to another form

  • and it is all around us

  4
• Change of energy:

  • Endothermic process/energy/reaction:

  * heat is absorbed from the surrounding;

  ** temperature of the surrounding decreases.

  *** system becomes hotter

  • Exothermic process/energy/reaction:

  * release heat to the surrounding;

  ** temperature of the surrounding increases.

  *** system becomes colder
• Change of energy has emphases on energy changes,

  particularly on the

  system’s energy exchange with

  its surroundings.
• The SI unit of energy is the joule, J or kJ
• CALORIE

  • non-SI unit of energy commonly used by

  chemists.

  • amount of energy required to raise the

  temperature of one gram of water by one

  degree Celsius.
• 1 cal = 4.184 J
• Potential Energy, Ep

  1. Chemical Energy

  2. Nuclear Energy

  3. Stored Mechanical Energy

  4. Gravitational Energy
• Potential Energy, Ep

  • Stored energy and the energy of position

  (gravitational)

  • Energy available by virtue of an objects position.

  • The energy an object has by virtue of its position

  in a field of force, such as gravitational, electric or

  magnetic field.
• Gravitational potential energy is given by the equation

  EP  mgh

  Where:

  m = mass (kg)

  g = gravitational constant (9.81 m/s2)

  h = height (m)
• Chemical Energy

  • Energy stored within the bonds of chemical substance.

  chemical bonding : ionic, covalent and metallic

  • It is stored within the structural units of chemical substances.

  • When substances participate in chemical reactions chemical energy is released,

  stored, or converted to other form of energies, and is transformed into an

  entirely new substance

  Applications:

  Biomass, petroleum, natural gas, propane and coal are few

  examples of store chemical energy
• Nuclear Energy (nuclear chemistry)

  • Energy stored within the collection of neutrons and protons in the

  atom.

  • Energy stored in the nucleus of an atom

  • Energy that holds the nucleus together

  Examples: energy of nucleus of elements
• STORED MECHANICAL ENERGY:

  • Energy stored in an object by the application of a force.

  Example: compressed spring;

  stretched rubber bands.
• Compression is the action of applying a force to a solid, liquid, or gas so that it takes up less space.
• Compression is the application of balanced inward ("pushing") forces to different points on a material or structure, that is, forces with no net sum or torque directed so as to reduce its size in one or more directions.
• Tension is a quantity associated with stretching or tensile forces.
• Tension is responsible for the elongation of the material along the axis of the applied load also called tensile stress.
• Shear is a deformation of a material substance in which parallel internal surfaces slide past one another.
• Torsion is a load that is a applied to a material through torque.
• The torque that is applied creates a shear stress.
• If a torsion force is large enough, it can cause a material to undergo a twisting motion during elastic and plastic deformation.
• Bending is a manufacturing process that produces a V-shape, U-shape, or channel shape along a straight axis in ductile materials.
• GRAVITATIONAL ENERGY:

  • Energy of place or position

  Example: water in a reservoir behind a hydropower dam.
• KINETIC ENERGY

  • 1. Radiant Energy

  • 2. Motion

  • 3. Sound

  • 4. Electrical Energy

  • 5. Thermal Energy
• Kinetic Energy, Ek

  • The energy associated with object by virtue of

  its motion

  Example: motion of waves, electrons,

  atoms, molecules and substances, water release

  to spin the turbine in a hydropower plant

  Its mathematical equation: EK=1/2

  mv²

  where:

  m = mass (kg)

  v = velocity (m/s)
• Radiant Energy (radiation)

  • Energy of electromagnetic energy that travels in transverse wave.

  Example:

  It’s solar energy and comes from the sun

  It’s primarily Energy Source for Earth

  It heats the atmosphere and surface of Earth

  Vegetation through photosynthesis

  • visible light, x-ray, gamma, rays, radio waves
• Motion and Sound

  MOTION:

  • Movement of the objects or substances from one place to another

  place

  Example: wind, hydropower

  SOUND:

  • Movement of energy through substances in longitudinal

  (compression/rarefaction) waves.
• Electrical Energy

  • Energy associated with the flow of electrons or

  movements of electrons

  Application: Electrochemistry

  Example: lightning, electricity
• Thermal Energy

  • energy contained within a system that is responsible for its temperature.

  • HEAT is the flow of thermal energy. Transformation of energy.

  • it’s the energy that is associated with the random motion of atoms and

  molecules

  • temperature is not the measurement of the thermal energy

  • it’s depend on quantity: Extensive property

  HEAT & THERMAL ENERGY are different
• Application of Energy

  Important application of energy are:

  Food energy --- energy that come from the food we eat

  Fuel energy ---- energy used in cooking food, producing

  electricity,

  moving vehicles like in land, air, water