Changing Shape (Edexcel GCSE Physics)

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Katie M

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Katie M

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Forces & Changing Shape

  • For stationary objects, multiple forces have to be applied to change their shape
  • Objects can change their shape by:

    • Stretching 
    • Bending 
    • Compressing 

  • A combination of all three shape changes can also occur

Compression

  • An object is compressed when forces act
    • In opposite directions
    • Towards the object
  • An example of compression is placing a mass on top of a spring placed on a flat surface
  • The two forces are:
    • The weight of the mass on the spring 
    • The reaction force of the surface on the spring

new-5-3-1-compressing-and-stretching-spring

The compression or stretching of a spring requires two forces

Stretching

  • An object is stretched when forces act:
    • In opposite directions
    • Away from the object
  • An example of stretching is placing a mass on the bottom of a spring hanging vertically from a rod
  • The two forces are:
    • The weight of the mass of the mass on the spring
    • The tension in the spring

  • These two opposing forces cause a tension force in the spring

Bending

  • An object is bent when multiple forces act:
    • In opposing directions
    • At different points on the object
  • An example of bending is a diving board bending when a swimmer stands at the far end
  • The two forces are:
    • The weight of the swimmer on the diving board
    • The reaction force of the block on the dividing board

Diving Board Bending, downloadable IGCSE & GCSE Physics revision notes

Forces on a diving board cause it to be bend when a swimmer stands on one end

bending-forces, IGCSE & GCSE Physics revision notes

More than one force on an object can cause it to bend

Elastic & Inelastic Distortion

  • When some objects, such as springs or rubber bands, are stretched they will return to their original shape and length once the forces are removed
    • Other materials, such as plastic, remain permanently distorted (stretched)

Elastic & Plastic, downloadable IGCSE & GCSE Physics revision notes

Elastic materials return to their original shape and size after stretching whilst plastic materials don’t

  • A change of shape is called a distortion and can either be:
    • Elastic
    • Inelastic

Elastic Distortion

  • Elastic distortion occurs:

When objects return to their original shape when the stretching force is removed

  • Examples of materials that undergo elastic distortion are:
    • Rubber bands
    • Fabrics
    • Steel springs

 

Inelastic Distortion

  • Inelastic distortion occurs:

When objects remain stretched and do not return completely to their original shape even when the stretching force is removed

  • Examples of materials that undergo inelastic distortion are:
    • Plastic
    • Clay
    • Glass

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Katie M

Author: Katie M

Expertise: Physics

Katie has always been passionate about the sciences, and completed a degree in Astrophysics at Sheffield University. She decided that she wanted to inspire other young people, so moved to Bristol to complete a PGCE in Secondary Science. She particularly loves creating fun and absorbing materials to help students achieve their exam potential.