Hooke's Law

• • The relationship between the extension of an elastic object and the force applied is defined by Hooke's Law
  • Hooke's Law states that:The extension of an elastic object is directly proportional to the force applied, up to the limit of proportionality
• Directly proportional means that as the force is increased, the extension increases 

  • If the force is doubled, then the extension will double
  • If the force is halved, then the extension will also halve
• • The limit of proportionality is the point beyond which the relationship between force and extension is no longer directly proportional 
  • This limit varies according to the material
• Hooke's Law states that a force applied to a spring will cause it to extend by an amount proportional to the force:

  
• • Hooke's Law is defined by the equation:

  F = k × x
• • Where:
  • F = force in newtons (N)
  • k = spring constant in newtons per metres (N/m)
  • x = extension in metres (m)
• • The symbol x can represent either the extension or compression of an elastic object
  • The Hooke's law equation can be rearranged using the following formula triangle:

  
• The spring constant represents how stiff the spring is

  • The higher the spring constant, the higher the stiffness
  • The extension of an object can be calculated by:

  Final length – Original length
• • The extension of the spring can be measured by marking the position of bottom of the unstretched spring
  • When the spring is stretched the final length must be measured from the bottom of the spring
• The extension measured from its final and original length: