# Physics - Oscillations

> Source: https://ollybritton.com/notes/a-level/physics/topics/oscillations/ · Updated: 2021-10-06 · Tags: school

## See Also
- [Physics - Circular Motion](https://ollybritton.com/notes/a-level/physics/topics/circular-motion/)

## Flashcards
##### What causes an object in an equilibrium position to start oscillating??
A force is applied that moves it from the equilibrium position.

##### How are circular motion and oscillations linked??
Measuring the displacement along the $x$-axis of an object moving in a circle forms an oscillating wave.

##### What is the formula for acceleration in simple harmonic motion??
$$
a = -\omega^2 x
$$

##### What is always true about the direction of displacement and direction of acceleration in simple harmonic motion??
They are opposites.

##### What is always true about simple harmonic motion??
The acceleration is directly proportional to the displacement.

### 2021-10-12
##### What is the formula for the maximum amplitude in simple harmonic motion (SMH)??
$$
a_{\text{max}} = A\omega
$$

##### What is the formula for the velocity in simple harmonic motion in terms of displacement $x$ and amplitude $A$??
$$
v = \pm \omega\sqrt{A^2 - x^2}
$$

##### What is the formula for the maximum velocity in simple harmonic motion??
$$
v = \omega r
$$

##### What is the formula for the displacement $x$ for simple harmonic motion at time $t$ if you begin timing when the displacement is at the maximum??
$$
x = A\cos(\omega t)
$$

##### What is the formula for the displacement $x$ for simple harmonic motion at time $t$ if you begin timing at the equilibrium position??
$$
x = A\sin(\omega t)
$$

##### What is the definition of simple harmonic motion??
Motion where the acceleration is directly proportional to the displacement and is directed towards the equilibrium position.

##### What is the graph of acceleration against displacement??
![PHOTO ACCELERATION DISPLACEMENT](a-x.png)

##### What is the graph of displacement against time, assuming you start measuring at the equilibrium position??
![PHOTO DISPLACEMENT TIME](x-t.jpg)

### 2021-10-13
##### When doing an oscillations question ($A\cos(\omega t)$, $A\sin(\omega t)$), what units should your calculator be in??
Radians!!

##### Why does your calculator have to be in radians for oscillation questions??
Because the angular frequency $\omega$ is in radians.

### 2021-10-15
##### If the amplitude of an oscillator is $0.25m$, how far does it move in one complete oscillation??
$$
1m
$$

##### If an oscillator has to overcome a mean dampening force of $0.25N$ for every $1m$ it moves per complete oscillation, what would be the formula for the energy expenditure per oscillation??
$$
0.25N \times 1m = 0.25J
$$

##### ![PHOTO PENDULUM ENERGY](pendulum-energy.png) What does this show??
How the energy of an oscillator changes (assuming you start measuring at the max).

##### What is the POTENTIAL energy of an oscillator at the EQUILIBRIUM position??
$$
0J
$$

##### What is the KINETIC energy of an oscillator at the EQUILIBRIUM position??
The max.

##### What is the POTENTIAL energy of an oscillator at the MAX position??
The max.

##### What is the KINETIC energy of an oscillator at the MAX position??
$$
0J
$$

##### What is always true about the total energy in an oscillator??
It remains constant.

### 2021-10-22
##### What is damping??
When an external force reduces the amplitude of an oscillator.

##### How does light damping affect the amplitude of an oscillator??
It gradually reduces it.

##### How does light damping affect the period of an oscillator??
It remains the almost the same.

##### How does heavy damping affect the amplitude of an oscillator??
It quickly reduces it.

##### How does heavy damping affect the period of an oscillator??
It gradually reduces it.

##### How does very heavy damping affect the amplitude of an oscillator??
It reduces it to $0$ and remains at the equilibrium position.

##### How does very heavy damping affect the period of an oscillator??
It stops being an oscillator.

##### What is a free oscillation??
Oscillatory motion with no external forces applied.

##### What is the frequency of free oscillation called??
The natural frequency.

##### What is a forced oscillation??
Oscillatory motion when an external driver force is applied.

##### What is the frequency of a forced oscillation??
The frequency of the driving force.

##### What is true about measuring the amplitude at period-length intervals if the oscillator is experiencing exponential damping??
There will be a constant ratio.

##### When does resonance occur??
When the driving frequency is the same as the natural frequency.

##### What happens when resonance occurs??
The amplitude of the oscillator will increase dramatically.

##### How can an opera singer break a wine glass??
They sing at the natural, resonant frequency of the glass.

### 2022-01-09
##### What is true about amplitude and period in SHM??
They are independent of one another.

##### What happens to the period of a pendulum if you raise the swinging bit further up (i.e. increase the amplitude)??
It remains the same.

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