Chapter 17 - Oscillations Flashcards
Angular frequency?
2 x pie x frequency
(2 x pie)/T
How do all oscillations begin?
With an object in equilibrium before a force is then applied to it (it then begins to displace)
Why does a pendulum travel quickest at point of equilibrium, when oscillating?
When displaced, it speeds up as it travels towards its equilibrium position and then increasingly slows down as it goes past it
What is displacement?
Distance from the equilibrium position (x)
What is amplitude?
Maximum displacement from the equilibrium position (A)
What is period?
Time take to complete one full oscillation
What is the frequency definition?
Number of complete oscillations per unit time
What do we use to compare the difference in displacement of two objects oscillating, or the difference for the same object at different times?
Phase difference
What is the phase difference of two objects in anti phase and what does this mean?
Pie radians - one object is at max pos displacement when the other is at max neg displacement
Definition of angular frequency?
Describes the motion of an oscillating object (closely related to angular velocity of an object in circular velocity)
What is simple harmonic motion?
Common kind of oscillating motion where its acceleration is defined as = -angular frequency*2 ( negative omega or W) x displacement
What is the constant in the acceleration for SHM?
W*2 (omega/angular frequency squared)
What is acceleration of an object directly proportional to?
Its displacement
What does the negative sign mean in SHM - negative omega*2 x displacement?
The acceleration of the object is proportional to the displacement, in the opposite direction it
What would the gradient of an acceleration vs displacement graph give?
The negative angular frequency squared
a/x = -W*2
Is the period of an oscillating object dependent on the amplitude?
No, as amplitude of the swing increases so does the average speed of the swing , therefore period doesn’t change (isochronous oscillator)
What shape is displacement vs time graph for SHM?
Sinusoidal shape, amplitudes K if no energy lost
Using displacement time graphs, how can you tell the speed is greatest when at 0 displacement?
The gradient equals velocity and the gradient is greatest when displacement = 0
At maximum displacements on a displacement time graph what can you tell?
The speed using the gradient - will be zero as motion has momentarily stopped
How can you use a displacement time graph to make a speed time graph?
Using the gradient of each time interval to plot the speed against time
How do you get an acceleration time graph using a speed time graph?
The gradient of the line at each time interval will give the acceleration at those times
Two equations to define displacement?
x=AcosWt
x=AsinWt
What do the letters stand for in x=A(sin or cos)Wt?
A = Amplitude W = Omega t = time
How do you know whether to use cos or sin displacement equation?
Use sin equation for when an object begins at equilibrium, cosine equation should be used when an object has been released from its max displacement
Calculation of the velocity of a simple harmonic motion?
v=±W(√A2-x2)
What is the vmax calculation?
v=WA (because x=0)
