Energy in Oscillations (Oxford AQA IGCSE Physics)

Energy in Oscillations

• An oscillating object moves back and forth in a regular rhythm

• The energy in an oscillating system is transferred back and forth between gravitational potential and kinetic energy stores

• Examples of oscillating objects are:

  • A simple pendulum

  • A guitar string

  • A swing

  • A bungee jump

  • A mass on a spring

  • Alternating current

• A simple pendulum consists of a mass (called a bob) on a string

• If the bob is displaced from its equilibrium position and left to swing freely, it will oscillate

A simple pendulum

• As the pendulum oscillates, energy is transferred back and forth between the gravitational potential and kinetic stores

• In an ideal system (where there is no air resistance) the total energy of the oscillating pendulum remains constant

• The position at which the pendulum would hang undisturbed is called the equilibrium position

• The pendulum is considered to have zero gravitational potential energy at the equilibrium position

• As the pendulum is displaced from the equilibrium position, energy is transferred to its gravitational potential store

• When the pendulum is released and begins to swing, energy is transferred from the gravitational potential store to the kinetic store

• The pendulum has the most kinetic energy as it swings through the equilibrium position because this is when its velocity is the greatest

• As it swings past the equilibrium position to the other side of the oscillation, energy is transferred from the kinetic store to the gravitational potential store

• As the pendulum bob reaches its point of maximum displacement from the equilibrium position, its velocity slows to zero (at the point at which it changes direction) so there is zero energy in its kinetic store and maximum energy in its gravitational potential store

Energy changes in an oscillating object