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Energy, Work and Power

  • Energy: amount of work and its measured in Joules (J)

  • Conservation of energy: energy cannot be created or destroyed, when work is done, energy is changed from one form to another.

    • Energy can be stored

  • A book on a shelf has g.p.e , if it falls of the shelf it will have k.e

Energy type

What it is

Kinetic

Due to motion

Gravitational

From potential to fall

Chemical

In chemical bonds

Strain

Compress/stretch

Nuclear

Atoms rearranged/split

Internal

Motion of molecules

Electrical

Carried by electrons

Light

Carried in light waves

Sound

Carried in sound waves

  • Due to the processes through which energy transfers take place not being 100% efficient

  • energy is lost to the surrounding and therefore energy gets more spread out (dissipated)

  • Efficiency: how much useful work is done with energy supplied

Energy Resources

  • Renewable sources: Energy sources that are not exhaustible/ Infinite

  • Non-renewable sources: Energy sources that are exhaustible/ finite

Work and Power

  • Work****: Work is done whenever a force acts on an object that moves (or is moving) in the direction of the force

    • The greater the force, the greater the work

    • The larger the distance moved, the larger the work

work-force-object, IGCSE & GCSE Physics revision notes

  • Whenever any work is done, energy gets transferred (mechanically) from one form to another

  • The amount of energy transferred (in joules) is equal to the work done (also in joules)

    • energy transferred (J) = work done (J)

Work done = Force x Distance travelled

  • Power: is the rate at which a machine transfers energy

  • The greater the rate at which energy is transferred, the greater the power

    • Because work done is equal to energy transferred, the power is also equal to the rate of doing work

  • Power = Energy/time

Energy, Work and Power

  • Energy: amount of work and its measured in Joules (J)

  • Conservation of energy: energy cannot be created or destroyed, when work is done, energy is changed from one form to another.

    • Energy can be stored

  • A book on a shelf has g.p.e , if it falls of the shelf it will have k.e

Energy type

What it is

Kinetic

Due to motion

Gravitational

From potential to fall

Chemical

In chemical bonds

Strain

Compress/stretch

Nuclear

Atoms rearranged/split

Internal

Motion of molecules

Electrical

Carried by electrons

Light

Carried in light waves

Sound

Carried in sound waves

  • Due to the processes through which energy transfers take place not being 100% efficient

  • energy is lost to the surrounding and therefore energy gets more spread out (dissipated)

  • Efficiency: how much useful work is done with energy supplied

Energy Resources

  • Renewable sources: Energy sources that are not exhaustible/ Infinite

  • Non-renewable sources: Energy sources that are exhaustible/ finite

Work and Power

  • Work****: Work is done whenever a force acts on an object that moves (or is moving) in the direction of the force

    • The greater the force, the greater the work

    • The larger the distance moved, the larger the work

work-force-object, IGCSE & GCSE Physics revision notes

  • Whenever any work is done, energy gets transferred (mechanically) from one form to another

  • The amount of energy transferred (in joules) is equal to the work done (also in joules)

    • energy transferred (J) = work done (J)

Work done = Force x Distance travelled

  • Power: is the rate at which a machine transfers energy

  • The greater the rate at which energy is transferred, the greater the power

    • Because work done is equal to energy transferred, the power is also equal to the rate of doing work

  • Power = Energy/time