Chapter 17 - Oscillations

Question 1

Angular frequency?

Answer 1

2 x pie x frequency

(2 x pie)/T

Question 2

How do all oscillations begin?

Answer 2

With an object in equilibrium before a force is then applied to it (it then begins to displace)

Question 3

Why does a pendulum travel quickest at point of equilibrium, when oscillating?

Answer 3

When displaced, it speeds up as it travels towards its equilibrium position and then increasingly slows down as it goes past it

Question 4

What is displacement?

Answer 4

Distance from the equilibrium position (x)

Question 5

What is amplitude?

Answer 5

Maximum displacement from the equilibrium position (A)

Question 6

What is period?

Answer 6

Time take to complete one full oscillation

Question 7

What is the frequency definition?

Answer 7

Number of complete oscillations per unit time

Question 8

What do we use to compare the difference in displacement of two objects oscillating, or the difference for the same object at different times?

Answer 8

Phase difference

Question 9

What is the phase difference of two objects in anti phase and what does this mean?

Answer 9

Pie radians - one object is at max pos displacement when the other is at max neg displacement

Question 10

Definition of angular frequency?

Answer 10

Describes the motion of an oscillating object (closely related to angular velocity of an object in circular velocity)

Question 11

What is simple harmonic motion?

Answer 11

Common kind of oscillating motion where its acceleration is defined as = -angular frequency*2 ( negative omega or W) x displacement

Question 12

What is the constant in the acceleration for SHM?

Answer 12

W*2 (omega/angular frequency squared)

Question 13

What is acceleration of an object directly proportional to?

Answer 13

Its displacement

Question 14

What does the negative sign mean in SHM - negative omega*2 x displacement?

Answer 14

The acceleration of the object is proportional to the displacement, in the opposite direction it

Question 15

What would the gradient of an acceleration vs displacement graph give?

Answer 15

The negative angular frequency squared

a/x = -W*2

Question 16

Is the period of an oscillating object dependent on the amplitude?

Answer 16

No, as amplitude of the swing increases so does the average speed of the swing , therefore period doesn’t change (isochronous oscillator)

Question 17

What shape is displacement vs time graph for SHM?

Answer 17

Sinusoidal shape, amplitudes K if no energy lost

Question 18

Using displacement time graphs, how can you tell the speed is greatest when at 0 displacement?

Answer 18

The gradient equals velocity and the gradient is greatest when displacement = 0

Question 19

At maximum displacements on a displacement time graph what can you tell?

Answer 19

The speed using the gradient - will be zero as motion has momentarily stopped

Question 20

How can you use a displacement time graph to make a speed time graph?

Answer 20

Using the gradient of each time interval to plot the speed against time

Question 21

How do you get an acceleration time graph using a speed time graph?

Answer 21

The gradient of the line at each time interval will give the acceleration at those times

Question 22

Two equations to define displacement?

Answer 22

x=AcosWt

x=AsinWt

Question 23

What do the letters stand for in x=A(sin or cos)Wt?

Answer 23

A = Amplitude
W = Omega 
t = time

Question 24

How do you know whether to use cos or sin displacement equation?

Answer 24

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

Question 25

Calculation of the velocity of a simple harmonic motion?

Answer 25

v=±W(√A2-x2)

Question 26

What is the vmax calculation?

Answer 26

v=WA (because x=0)