Simple Harmonic Motion
Learning Outcomes (LOs)
- describe simple examples of free
oscillations.
- investigate the motion of an
oscillator using experimental and graphical methods.
- understand and use the terms
amplitude, period, frequency and angular frequency.
- recognise and use the equation a
= - ω2 x as the defining equation of simple harmonic motion.
- recall and use x= x0
ω sin( ωt )as a solution to the equation a = - ω2 x
- recognise and use v = v0
cos ( ω t ) ,
- describe with graphical
illustrations, the changes in displacement, velocity and acceleration
during simple harmonic motion.
- describe the interchange between
kinetic and potential energy during simple harmonic motion.
- describe practical examples of
damped oscillations with particular reference to the effects of the
degree of damping and the importance of critical damping in cases such
as a car suspension system.
- describe practical examples of
forced oscillations and resonance.
- show an appreciation that there
are some circumstances in which resonance is useful and other
circumstances in which resonance should be avoided.
- describe graphically how the
amplitude of a forced oscillation changes with frequency near to the
natural frequency of the system, and understand qualitatively the
factors which determine the frequency response and sharpness of the
resonance.
Simple examples of free oscillations LO(a)
Example 1: Simple pendulum
static picture of a pendulum bob given an initial horizontal displacement
and released to swing freely to produce to and fro motion
dynamic picture of a pendulum bob given an initial horizontal displacement
and released to swing freely to produce to and fro motion
http://dl.dropboxusercontent.com/u/44365627/lookangEJSworkspace/export/ejss_model_SHM01/SHM01_Simulation.xhtml
Q1: what is the maximum angle of release before the motion is not accurately
described as a simple harmonic motion for the case of a simple free
pendulum?
A1: : 10 degrees for error of , depending on what is the error acceptable,
small angle is typically about less than 10 degree of swing from the
vertical.