Vibrations / Oscillations

• Simple Harmonic Motion


  Where an object moves so that its acceleration is proportional to its displacement from a fixed point and acceleration is directed toward a fixed point
• At max displacement, velocity is 0 and acceleration is at a maximum
• When the displacement is 0, the acceleration is 0 and velocity is at a maximum
• Damping is the reduction in amplitude due to resistive forces, with the period remaining unaffected
• Critical damping is where the resistive forces are just large enough to prevent oscillations occurring at all when the system is displaced and released
• Critical damping is used in a train buffer, stopping the train from rebounding or going straight through the buffer
• Free oscillations is where an object oscillates continually as there are no resistive forces, oscillating at its natural frequency
• Forced Oscillations is when a driving force causes the system to oscillate at the same frequency as the driving force
• Resonance is where a driving force is close to the natural frequency of the system, causing a large amplitude
• An example of resonance is pushing a person on a swing, only pushing when they reach the highest point of their motion, causing them to swing higher