# 19.1.1 Oscillations & Simple Harmonic Motion

### Free Oscillations

• A free oscillation is defined as:

A vibration with no external forces acting on it

• A free oscillation has constant energy and amplitude ie. no energy loss or gain
• An example of a free oscillation is a plucked guitar string
• It will vibrate for some time after it is plucked and released
• Free oscillators vibrate at a particular frequency
• This is called the natural frequency of the vibration
• Every oscillator has a natural frequency of vibration
• This is the frequency in which it vibrates freely after an initial disturbance

### Motion of an Oscillator

• An experimental and graphical method can be used to observe the motion of a simple mass-spring system
• Tie a pencil together with the mass and set the mass in free oscillations by displacing it downwards slightly
• The oscillations will move the pencil up and down
• On a piece of graph paper, allow the pencil to trace the path of the oscillations by pulling the paper sideways as the mass-spring system oscillates up and down
• The oscillations will produce a curved, periodic graph
• This will decrease in amplitude as the mass-spring system slows down

### Author: Katie

Katie has always been passionate about the sciences, and completed a degree in Astrophysics at Sheffield University. She decided that she wanted to inspire other young people, so moved to Bristol to complete a PGCE in Secondary Science. She particularly loves creating fun and absorbing materials to help students achieve their exam potential.
Close