Forces and Elasticity

• A Deformation can be Elastic or Plastic
• Deformation


  When you apply forces to an object, it can be stretched, compressed, or bent
• If an object returns to its original shape after the forces are removed, it's an elastic deformation
• If the object does not return to its original shape when you remove the forces, it's plastic deformation
• The relationship between the extension of a spring and the force is called Hooke's law
• Hooke's law stops working when the force is great enough
• Most objects still deform elastically for a little bit after reaching the limit of proportionality
• When the elasticity of an object ends, it starts to deform plastically and may spring back to its original shape
• The maximum force that can be applied to a material before plastic deformation occurs is called its elastic limit
• The gradient of a force-extension graph for a material obeying Hooke's law is also the spring constant
• Equation for force exerted by a spring

  Force exerted by spring (N) = Spring constant (N/m) x Extension (m)
• The force exerted by a spring is directly proportional to the extension
• Limit of proportionality

  The maximum force that can be applied by a spring before it breaks hookes law, becoming non-linear and going through plastic deformation
• A stiffer spring will have a lower spring constant