Chapter 15- Oscillations Flashcards Preview

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Flashcards in Chapter 15- Oscillations Deck (35)
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1
Q

Amplitude

A

Max displacement from the equilibrium position

In metres

2
Q

Period

A

The time taken to complete one oscillation T

In seconds

3
Q

Frequency

A

The number of complete oscillations per second

In Hz

4
Q

Two types of oscillations

A
  • pendulum

* spring

5
Q

Period, frequency eq

A

F= 1/T

6
Q

Simple harmonic motion is

A

The periodic motion about an equilibrium position such that acceleration (Fresultant=ma)is:
• proportional to the displacement
• always directed towards the fixed point

7
Q

SHM equation

A

F= -kx (k is a constant)

F is always opposite in direction to displacement

8
Q

F= -kx equation becomes

A

a= -w^2 x

9
Q

SHM oscillation period equation

A

T= 2pie ✅m/k

10
Q

Simple pendulum

What does simple mean?(2)

A
  • small, dense pendulum bob

* light inextensible string

11
Q

SHM oscillation equation for period on a pendulum

A

T= 2pie✅L/g

L= length of string from attached point 
G= grav
12
Q

Graph of -w^2A against x

A

= a negative straight line

= inversely proportional

13
Q

Equations regarding x= and v=

A

X= Acoswt

V= -wAsinwt

14
Q

Displacement for pendulum bob

A

Always from the equilibrium point

15
Q

In oscillation velocity is at max when…

A

In the central position

16
Q

In oscillation velocity is 0 when..

A

At the end of the oscillation
When displacement is at maximum (+ve/-ve)
Gradient is zero

17
Q

The gradient of a velocity time graph

A

Acceleration

18
Q

Acceleration eq combing all the others

A

a= -w^2Acoswt

Because differentiate sin and you get cos

v= -wAsinwt
x= Acoswt
a= -w^2x
19
Q

w equation

A

w= 2pie f

Or

w= 2pie/ T

20
Q

As a pendulum swings to and fro there is a continuous interchange of

A

Kinetic and gravitational potential energy

21
Q

Potential energy at max when

A

Pendulum is at max displacement

22
Q

Pendulum has max KE when

A

In central equilibrium position

23
Q

Interchange between PE and KE is repeated _____ every oscillation

A

Twice every oscillation

24
Q

From eq v= -wAsinwt

Max velocity value will be when sinwt = +1/-1

Giving…

A

Vmax= +/- wA

25
Q

Max KE is when…

Equation is therefore…

A

When V is at its max

KE= 1/2 mv^2 = 1/2 m( -wA)^2

= 1/2 mw^2A^2

26
Q

Law of conservation of energy means that within an oscillation

A

E kinetic + E potential = E total

Curve for both on graph
Happy face and sad face

27
Q

Free oscillation def

A

One which no external force acts on the oscillating system except forces that give rise to the oscillation

28
Q

Damped oscillation def

A

One in which energy is being transferred to surroundings resulting in oscillations of reduced amplitude and energy

29
Q

Forced oscillations

A

Occur if force is continually applied to keep oscillation going
Same frequency as vibrating source
Not at own natural frequency

30
Q

The damping graph shape is

A

Exponential

Can take log of it and plot to find straight line
Or look at ratios

31
Q

A pendulum of the same natural frequency will absorb

A

The most energy and will be forced to oscillate with much larger amplitude
= called resonance

32
Q

Resonance def

A

Oscillating system is forced to oscillate by an outside source at a frequency the same as its own natural frequency

33
Q

Maximum energy transfer or energy resonance always occurs at

A

The natural frequency

34
Q

If there is no damping

A

Then max amplitude resonance occurs when driving frequency is equal to the natural frequency of vibration of the mass

35
Q

If there is damping

A

The resonant frequency at which amplitude is max is lower than the natural frequency

Difference increases as damping increases