Work and Energy

• What is Hooke’s Law?

  Elastic objects can be stretched but will not return to its original shape if elastic limit is reached
• What is the stretch of a spring directly proportional to?

  The mass i.e. double mass = double extention
• What will happen to an overstretched spring?

  It will not return to its original shape
• That does it mean if a spring has been overstretched?

  It has reached its elastic limit
• Stiffer springs have a greater spring constant
• How do you calculate spring constant? (k)


  Force/Extension F/x
• Stiffer spring = steeper gradient
• What will adding more springs do?

  Increases the spring constant
• What is spring constant?

  The spring constant is a measure of the stiffness of a spring and is defined as the force required to stretch or compress the spring by a certain amount
• What will happen to the line on a graph when the spring reaches its elastic limit?

  It begins to curve (stops obeying Hooke’s Law)
• On a graph, when more springs are added and the spring constant increases, the proportional relationship on the graph will be the same, but the extension will be halved
• What is the law of conservative energy?

  • Energy cannot be created or destroyed, only converted from one form to another
  • The total energy at the start must be the same as the end
  • Energy can be converted
  • We can lift something high and give it gravitational potential energy
  • It is potential as we could leave it somewhere e.g. on a shelf, or we could let it fall off and convert the energy to kinetic