RP07 - Simple Harmonic Motion

• What is simple harmonic motion?

  • Simple harmonic motion is any periodic motion where the object's acceleration is proportional to and in the opposite direction of the displacement
  • This results in oscillatory behaviour
• What is the relationship between a pendulum's time period and its mass?

  The time period of a pendulum is independent of its mass
• What two conditions must be met when carrying out a simple harmonic motion experiment involving a pendulum?

  • The amplitude of oscillation should be small
  • The pendulum should oscillate in a straight line
• Why must the oscillations only be small when carrying out this experiment?

  • The equations are derived using a small angle approximation
  • So it only applies for relatively small displacements
• How should you measure the time period of an oscillating simple pendulum?

  • Measure the time taken for the pendulum to complete 10 full oscillations
  • Repeat this measurement three times and then calculate an average time
  • Divide this average by 10 to measure the average time period for one oscillation
• What could be added to your apparatus to help measure the time period more accurately?

  A fiducial marker, such as a small pin, could be added at the centre of oscillation to show exactly when an oscillation has been completed
• When plotting a graph T^2 against L, what does a straight line passing through the origin demonstrate?

  A straight line through the origin shows that T^2 is directly proportional to L
• Describe how the time period of a simple mass spring oscillator varies with the length of the spring

  • The time period of a mass-spring oscillator does not depend on the length of the spring
  • It only depends on the mass and the spring constant
• When hanging a mass-spring system from a clamp stand, what safety precaution should be taken?

  A counterweight or G-clamp should be used to provide a counter moment on the clamp stand so as to prevent it from toppling
• What safety precaution should be taken when adding masses to a spring?

  • Safety goggles should be worn in case the spring snaps
  • It is also important to ensure you never stand with your feet directly below the masses in case they fall