forces & elasticity

• what are examples of forces involved in deforming objects?

  • stretching
  • bending
  • compressing
• what is stretching and what forces does it involve?

  pulling a spring or elastic band apart involves tension forces
• what is bending and what forces does it involve?

  applying forces to bend a beam or ruler involves opposite forces at both ends
• what is compressing and what forces does it involve?

  squashing an object (e.g. a sponge) involves compression forces
• how many forces are needed to change the shape of an object?


  more than one
• what are examples of why more than one force is needed to change the shape of an object?

  • stretching a spring requires pulling forces applied in opposite direction
  • bending a beam involves opposite forces applied at both ends
• why are multiple forces needed for only stationary objects?

  because a single force would cause the object to move rather than deform
• what is elastic deformation?

  the object returns to its original shape after the forces are removed
• what is inelastic deformation?

  the object does not return to its original shape after the forces are removed
• the extension of an elastic object is ________ ____________ to the force applied

  directly proportional
• how do you calculate the extension of an elastic object when a force is applied?

  force = spring constant X extension

  F = k X e
• force (F) is in?

  newtons (N)
• spring constant (k) is in?


  newtons per metre (N/m)
• extension (e) is in?

  metres (m)
• the relationship between force and extension applies not only to stretching a spring but also to ___________ an elastic object


  compressing
• how can you calculate work done in stretching (or compressing) a spring?

  elastic potential energy = 0.5 X spring constant X (extension) squared