Energy, Work & Power Chapter Notes | Physics for GCSE/IGCSE - Year 11 PDF Download

 Page 1


Energy transformations and energy transfers
? Energy is the capacity of something to do work
? Law of conservation of energy
? Energy cannot be created or destroyed, it can only change from one form to another
Types of energy / energy stores
? Elastic energy
? Energy stored in a compressed material is called elastic energy
? Internal energy
? It is the energy of a substance due to the kinetic energy or movement of its particles
? Highest in gases
? Chemical energy
? The energy stored in the bonds of atoms and molecules in an object and it is released in
chemical reaction
? Nuclear energy
? Energy released from nucleus of an atom
? Nuclear fission
¦ The splitting up of heavier nucleus into 2 or more lighter nuclei and releases a large
amount of heat energy
¦ Working principle of atom bomb
¦ ? ? Fission  Uranium + neutron  Barium + krypton + 3 neutrons + heat
? Nuclear fusion
¦ The process combining 2 or more lighter nuclei to form a heavier nucleus and
release a large amount of nuclear energy
¦ Working principle of hydrogen
¦ ? ? Fusion  Hydrogen nucleus + hydrogen  Helium + heat/light energy
? Gravitational Potential energy(GPE)
? Energy something gains when you lift an object up and loses when it falls
? ? G.P.E  weight x height mass x height x gravity or
? Higher the object from the ground, the more the GPE
Page 2


Energy transformations and energy transfers
? Energy is the capacity of something to do work
? Law of conservation of energy
? Energy cannot be created or destroyed, it can only change from one form to another
Types of energy / energy stores
? Elastic energy
? Energy stored in a compressed material is called elastic energy
? Internal energy
? It is the energy of a substance due to the kinetic energy or movement of its particles
? Highest in gases
? Chemical energy
? The energy stored in the bonds of atoms and molecules in an object and it is released in
chemical reaction
? Nuclear energy
? Energy released from nucleus of an atom
? Nuclear fission
¦ The splitting up of heavier nucleus into 2 or more lighter nuclei and releases a large
amount of heat energy
¦ Working principle of atom bomb
¦ ? ? Fission  Uranium + neutron  Barium + krypton + 3 neutrons + heat
? Nuclear fusion
¦ The process combining 2 or more lighter nuclei to form a heavier nucleus and
release a large amount of nuclear energy
¦ Working principle of hydrogen
¦ ? ? Fusion  Hydrogen nucleus + hydrogen  Helium + heat/light energy
? Gravitational Potential energy(GPE)
? Energy something gains when you lift an object up and loses when it falls
? ? G.P.E  weight x height mass x height x gravity or
? Higher the object from the ground, the more the GPE
? Kinetic energy
? The energy of a moving object / energy possessed by an object due to its movement or
motion
? ? K.E  ½ x mass x velocity^2
? Mass = 2K.E/ V^2
? Velocity = 2K.E/mass
Types of energy transfers
? Light energy
? Light is an electromagnetic radiation
? Speed of light is 3 x 10^8
? Thermal/ heat energy
? Energy transferred between 2 objects at different temperatures
? It is not continued within the object, it is transferred between 2 objects.
? Electrical energy
? It is produced by the flow of electrons
? It is a type of energy transfer
? Sound energy
? It requests a medium to propagate(transmit)
? Produced by vibration of objects
? Energy can be transferred through 4 ways
? Force
¦ When a force acts on a body, energy can be transferred between 2 forms
? Heat
¦ Internal energy can be transferred from place to place by the processes of
conduction, convection and thermal radiation
? Radiation
¦ Light and sound carry energy therefore can transfer it between places
(electromagnetic radiation)
? Electricity
¦ Electricity can transfer energy from a power source, delivering it to components
within a circuit
? ? Chemical energy  K.E +G.P.E + heat energy + sound energy
? ? Elastic energy  Electrical + thermal energy/ Sound + thermal energy
Page 3


Energy transformations and energy transfers
? Energy is the capacity of something to do work
? Law of conservation of energy
? Energy cannot be created or destroyed, it can only change from one form to another
Types of energy / energy stores
? Elastic energy
? Energy stored in a compressed material is called elastic energy
? Internal energy
? It is the energy of a substance due to the kinetic energy or movement of its particles
? Highest in gases
? Chemical energy
? The energy stored in the bonds of atoms and molecules in an object and it is released in
chemical reaction
? Nuclear energy
? Energy released from nucleus of an atom
? Nuclear fission
¦ The splitting up of heavier nucleus into 2 or more lighter nuclei and releases a large
amount of heat energy
¦ Working principle of atom bomb
¦ ? ? Fission  Uranium + neutron  Barium + krypton + 3 neutrons + heat
? Nuclear fusion
¦ The process combining 2 or more lighter nuclei to form a heavier nucleus and
release a large amount of nuclear energy
¦ Working principle of hydrogen
¦ ? ? Fusion  Hydrogen nucleus + hydrogen  Helium + heat/light energy
? Gravitational Potential energy(GPE)
? Energy something gains when you lift an object up and loses when it falls
? ? G.P.E  weight x height mass x height x gravity or
? Higher the object from the ground, the more the GPE
? Kinetic energy
? The energy of a moving object / energy possessed by an object due to its movement or
motion
? ? K.E  ½ x mass x velocity^2
? Mass = 2K.E/ V^2
? Velocity = 2K.E/mass
Types of energy transfers
? Light energy
? Light is an electromagnetic radiation
? Speed of light is 3 x 10^8
? Thermal/ heat energy
? Energy transferred between 2 objects at different temperatures
? It is not continued within the object, it is transferred between 2 objects.
? Electrical energy
? It is produced by the flow of electrons
? It is a type of energy transfer
? Sound energy
? It requests a medium to propagate(transmit)
? Produced by vibration of objects
? Energy can be transferred through 4 ways
? Force
¦ When a force acts on a body, energy can be transferred between 2 forms
? Heat
¦ Internal energy can be transferred from place to place by the processes of
conduction, convection and thermal radiation
? Radiation
¦ Light and sound carry energy therefore can transfer it between places
(electromagnetic radiation)
? Electricity
¦ Electricity can transfer energy from a power source, delivering it to components
within a circuit
? ? Chemical energy  K.E +G.P.E + heat energy + sound energy
? ? Elastic energy  Electrical + thermal energy/ Sound + thermal energy
? In any conversion, the total amount of energy before and after the conversion is constant
? Sankey diagram
? It is used to show energy transfer
? It is used to show how much input energy is being used and how much is actually being
wasted
? The thicker the line, the more the energy
? Efficiency
? The efficiency of a system is the percentage of energy transferred from the original
store that ends up in the intended form
? ? Efficiency  Useful energy output/ Total energy input x 100
? In percentage
? Generator / Turbine
? ? Mechanical  mechanical + electricity
? Thermal power plant
? ? ? ? Chemical  thermal  mechanical  electrical
? Nuclear reaction
? ? ? ? Nuclear  thermal  mechanical  electrical
? Windmill
? ? ? ? Mechanical  Mechanical  Mechanical  Electrical
Page 4


Energy transformations and energy transfers
? Energy is the capacity of something to do work
? Law of conservation of energy
? Energy cannot be created or destroyed, it can only change from one form to another
Types of energy / energy stores
? Elastic energy
? Energy stored in a compressed material is called elastic energy
? Internal energy
? It is the energy of a substance due to the kinetic energy or movement of its particles
? Highest in gases
? Chemical energy
? The energy stored in the bonds of atoms and molecules in an object and it is released in
chemical reaction
? Nuclear energy
? Energy released from nucleus of an atom
? Nuclear fission
¦ The splitting up of heavier nucleus into 2 or more lighter nuclei and releases a large
amount of heat energy
¦ Working principle of atom bomb
¦ ? ? Fission  Uranium + neutron  Barium + krypton + 3 neutrons + heat
? Nuclear fusion
¦ The process combining 2 or more lighter nuclei to form a heavier nucleus and
release a large amount of nuclear energy
¦ Working principle of hydrogen
¦ ? ? Fusion  Hydrogen nucleus + hydrogen  Helium + heat/light energy
? Gravitational Potential energy(GPE)
? Energy something gains when you lift an object up and loses when it falls
? ? G.P.E  weight x height mass x height x gravity or
? Higher the object from the ground, the more the GPE
? Kinetic energy
? The energy of a moving object / energy possessed by an object due to its movement or
motion
? ? K.E  ½ x mass x velocity^2
? Mass = 2K.E/ V^2
? Velocity = 2K.E/mass
Types of energy transfers
? Light energy
? Light is an electromagnetic radiation
? Speed of light is 3 x 10^8
? Thermal/ heat energy
? Energy transferred between 2 objects at different temperatures
? It is not continued within the object, it is transferred between 2 objects.
? Electrical energy
? It is produced by the flow of electrons
? It is a type of energy transfer
? Sound energy
? It requests a medium to propagate(transmit)
? Produced by vibration of objects
? Energy can be transferred through 4 ways
? Force
¦ When a force acts on a body, energy can be transferred between 2 forms
? Heat
¦ Internal energy can be transferred from place to place by the processes of
conduction, convection and thermal radiation
? Radiation
¦ Light and sound carry energy therefore can transfer it between places
(electromagnetic radiation)
? Electricity
¦ Electricity can transfer energy from a power source, delivering it to components
within a circuit
? ? Chemical energy  K.E +G.P.E + heat energy + sound energy
? ? Elastic energy  Electrical + thermal energy/ Sound + thermal energy
? In any conversion, the total amount of energy before and after the conversion is constant
? Sankey diagram
? It is used to show energy transfer
? It is used to show how much input energy is being used and how much is actually being
wasted
? The thicker the line, the more the energy
? Efficiency
? The efficiency of a system is the percentage of energy transferred from the original
store that ends up in the intended form
? ? Efficiency  Useful energy output/ Total energy input x 100
? In percentage
? Generator / Turbine
? ? Mechanical  mechanical + electricity
? Thermal power plant
? ? ? ? Chemical  thermal  mechanical  electrical
? Nuclear reaction
? ? ? ? Nuclear  thermal  mechanical  electrical
? Windmill
? ? ? ? Mechanical  Mechanical  Mechanical  Electrical
Work and power
? Work is the transfer of energy through motion
? Amount of force depends on 2 things
? The amount of force exerted
? The distance over which the force is applied
? If you push a box with force 1 newton for a distance of 1 meter, you have done 1 joule of work
? ? Work  Force x Distance
(joules)    (Newton)   (metre)
? Work(force at angle to distance)
? Force x Distance x Cos
? Work done against gravity
? Mass x gravity x height (mgh)
? Power
? The rate at which work is done
? The rate at which energy is expanded or absorbed
? Power = Energy transferred/time
? Power = Change in work/time
Page 5


Energy transformations and energy transfers
? Energy is the capacity of something to do work
? Law of conservation of energy
? Energy cannot be created or destroyed, it can only change from one form to another
Types of energy / energy stores
? Elastic energy
? Energy stored in a compressed material is called elastic energy
? Internal energy
? It is the energy of a substance due to the kinetic energy or movement of its particles
? Highest in gases
? Chemical energy
? The energy stored in the bonds of atoms and molecules in an object and it is released in
chemical reaction
? Nuclear energy
? Energy released from nucleus of an atom
? Nuclear fission
¦ The splitting up of heavier nucleus into 2 or more lighter nuclei and releases a large
amount of heat energy
¦ Working principle of atom bomb
¦ ? ? Fission  Uranium + neutron  Barium + krypton + 3 neutrons + heat
? Nuclear fusion
¦ The process combining 2 or more lighter nuclei to form a heavier nucleus and
release a large amount of nuclear energy
¦ Working principle of hydrogen
¦ ? ? Fusion  Hydrogen nucleus + hydrogen  Helium + heat/light energy
? Gravitational Potential energy(GPE)
? Energy something gains when you lift an object up and loses when it falls
? ? G.P.E  weight x height mass x height x gravity or
? Higher the object from the ground, the more the GPE
? Kinetic energy
? The energy of a moving object / energy possessed by an object due to its movement or
motion
? ? K.E  ½ x mass x velocity^2
? Mass = 2K.E/ V^2
? Velocity = 2K.E/mass
Types of energy transfers
? Light energy
? Light is an electromagnetic radiation
? Speed of light is 3 x 10^8
? Thermal/ heat energy
? Energy transferred between 2 objects at different temperatures
? It is not continued within the object, it is transferred between 2 objects.
? Electrical energy
? It is produced by the flow of electrons
? It is a type of energy transfer
? Sound energy
? It requests a medium to propagate(transmit)
? Produced by vibration of objects
? Energy can be transferred through 4 ways
? Force
¦ When a force acts on a body, energy can be transferred between 2 forms
? Heat
¦ Internal energy can be transferred from place to place by the processes of
conduction, convection and thermal radiation
? Radiation
¦ Light and sound carry energy therefore can transfer it between places
(electromagnetic radiation)
? Electricity
¦ Electricity can transfer energy from a power source, delivering it to components
within a circuit
? ? Chemical energy  K.E +G.P.E + heat energy + sound energy
? ? Elastic energy  Electrical + thermal energy/ Sound + thermal energy
? In any conversion, the total amount of energy before and after the conversion is constant
? Sankey diagram
? It is used to show energy transfer
? It is used to show how much input energy is being used and how much is actually being
wasted
? The thicker the line, the more the energy
? Efficiency
? The efficiency of a system is the percentage of energy transferred from the original
store that ends up in the intended form
? ? Efficiency  Useful energy output/ Total energy input x 100
? In percentage
? Generator / Turbine
? ? Mechanical  mechanical + electricity
? Thermal power plant
? ? ? ? Chemical  thermal  mechanical  electrical
? Nuclear reaction
? ? ? ? Nuclear  thermal  mechanical  electrical
? Windmill
? ? ? ? Mechanical  Mechanical  Mechanical  Electrical
Work and power
? Work is the transfer of energy through motion
? Amount of force depends on 2 things
? The amount of force exerted
? The distance over which the force is applied
? If you push a box with force 1 newton for a distance of 1 meter, you have done 1 joule of work
? ? Work  Force x Distance
(joules)    (Newton)   (metre)
? Work(force at angle to distance)
? Force x Distance x Cos
? Work done against gravity
? Mass x gravity x height (mgh)
? Power
? The rate at which work is done
? The rate at which energy is expanded or absorbed
? Power = Energy transferred/time
? Power = Change in work/time
? ? 1 horsepower  746 watts
? ? 1 watt  1 joule per second
? Efficiency
? ? Efficiency  useful Energy output/Energy input x 100
? ? Efficiency  useful Power output/Power input  x 100