Term 2 Week 4 2020

Homework

• Ex 3D, p.66--67, Wave Properties
• Ex 3E, p.69-70, Diffration
• Ex 3F, p.3F, p.73-75 Superposition
• Ex 3G, p.76-78 Two Point Source Interference
• Ex 3H, p.81-83 Waves on a String
• Ex 3I, p.85-87 Wave Refraction on a String
• Ex 3B, p. 47-52, Refraction

Diffraction

• The Bending of Waves Around Corners
• Larger Wavelength, 𝛌 - greater the angle of diffraction
• Shorter Wavelength, 𝛌 - smaller the angle of diffraction
• Also the smaller the gap the greater the angle of diffraction

Diffraction

Diffraction of Water Waves in a Ripple Tank

Two Point Source Interference

Two Point Source Interference

Double Slit Experiment

PhET Sound Wave Interference - link

PhET Wave Interference - link HTML

Cymatics

Cymatics

Cymatics: Hose Pipe Water Experiment

Singing plates - Standing Waves on Chladni plates

Cymatics: Ruben's Tube Vs. Tesla Coil

Sound + Fire = Rubens' Tube

A better description of resonance

Snell's Law & Critical Angle

The Critical Angle occurs when a wave is attempting to pass from a medium with a slower speed to that of a higher speed 

low v → higher v

low 𝜆 → higher 𝜆

high n → lower n

The Critical angle is the incident angle where the refracted angle equals 90 degrees

Refraction Bending Light PhET Application

Snell's Law

• Any incident above the Critical angle will prevent any refraction occuring and Total Internal Reflection will occur
• The Critical angle is can be found by sin(𝜭c) = n2/n1

FibreOptic Cables: How they work?

Total Internal Reflection T.I.R.

What Happens to Lazers Underwater?

Term 2 Week 3 2020

Homework

• Ex 3D, p.66--67, Wave Properties
• Ex 3E, p.69-70, Diffration
• Ex 3F, p.3F, p.73-75 Superposition

Basic Properties of Waves

waves transfer energy through a medium without transferring the medium itself

• Cycle - a basic repeating unit in a wave
• Amplitude A (m) - the distance from the middle point to the top of a crest, or bottom of a trough
• Wavelength 𝜆 (m) - the distance/length of one cycle
• Period T (s = s per cycle) - the time it takes for one cycle to pass a point
• Frequency f (Hz = cycles per second) - the number of cycles that pass in one second

T = 1/f & f = 1/T

• Wave Speed v (ms-1) the speed of a wave

v = 𝜆/T & v = f𝜆

Wave Properties

Frequency & Period

Wave Phase

Pendulum Waves

Longitudinal Waves

particle displacement in the medium is parallel to the direction of wave propagation e.g. sound waves, primary earthquake waves

Transverse Waves

particle displacement in the medium is perpendicular to the direction of wave propagation e.g. light and other electromagnetic waves, secondary earthquake waves

• Superposition of Waves: two waves traveling through each other will not change each other motion in any way, but they will add to one another when they overlap
• Constructive Interference - Reinforcement - In Phase
• Destructive Interference - Cancellation - Out of Phase

PhET Waves on a String App - link

Reflection on A String

Hard Boundary

Wave reflects on opposite side (opposite phase)

Same Amplitude, A

Same Wavelength, 𝛌

Same Wave Speed, v

Reflection on A String

Soft Boundary

Wave reflects on same side (same phase)

Same Amplitude, A

Same Wavelength, 𝛌

Same Wave Speed, v

Refraction on A String

Fast to Slow Boundary

Relation of waves to Incident Wave

Reflected Wave - same speed - same wavelength 𝛌 - opposite phase

Refracted Wave - slower speed - smaller wavelength 𝛌 - same phase

Refraction on A String

Slow to Fast Boundary

Relation of waves to Incident Wave

Reflected Wave - same speed - same wavelength 𝛌 - same phase

Refracted Wave - faster speed - larger wavelength 𝛌 - same phase

Term 2 Week 1 2020

Homework:

• Ex 4E, p.115-117 Kinematics (earlier week)
• Ex 4F, p.119-124 Projectile Motion (earlier week)
• Ex 4A, p.90-94 Vectors (earlier week)
• Ex 4H, p.132-134, Circular Motion (earlier week)
• Ex 4B, p.97-104 Forces (earlier week)
• Ex 4F, p.143-147 Energy, Work, Power (earlier week)
• Ex 4I, p.137-141, Springs (earlier week)
• Ex 2B, p.16-18, Graphing(Complete these for the upcomming Lab Assessment)
• Ex 2C, p.19-25, Identifying Relationships and Experimental Equations(Complete these for the upcomming Lab Assessment)
• Ex 2B, p.23-40, Level 3 Handout booklet on Graphing Errors (Complete these for the upcomming Lab Assessment)
• Ex 4D, p.108-112, Momentum P = mv (earlier week)
• Ex 4C, p.105-107, Impulse ΔP = FΔt (earlier week)
• Ex 4G, p.125-130, Torque - Static Moments (this week)
Torque

𝝉 = F L⦜
𝝉: Torque (Nm)
F: applied Force (N)
L⦜: Length of lever at right angles to the applied force (m)


• Torque (Moments) in Level 2 Physics will involve Static Systems
• Therefore the Torques are balanced and the Forces are balanced - Newton's Laws of Motion apply to turning forces as well as linear forces
• PhET - Torque Balancing Act simulation
Bridge support forces moments


Torque (Moments anout a point)
Static (unmoving) systems will be used for this section. Therefore all forces, linear and turning, are balanced








Torque

Term 1 Week 9 2020

Homework:

• Ex 4E, p.115-117 Kinematics (earlier week)
• Ex 4F, p.119-124 Projectile Motion (earlier week)
• Ex 4A, p.90-94 Vectors (earlier week)
• Ex 4H, p.132-134, Circular Motion (earlier week)
• Ex 4B, p.97-104 Forces (earlier week)
• Ex 4F, p.143-147 Energy, Work, Power (earlier week)
• Ex 4I, p.137-141, Springs (earlier week)
• Ex 2B, p.16-18, Graphing(Complete these for the upcomming Lab Assessment)
• Ex 2C, p.19-25, Identifying Relationships and Experimental Equations(Complete these for the upcomming Lab Assessment)
• Ex 2B, p.23-40, Level 3 Handout booklet on Graphing Errors (Complete these for the upcomming Lab Assessment)
• Ex 4D, p.108-112, Momentum P = mv (this week)
• Ex 4C, p.105-107, Impulse ΔP = FΔt (this week)


Momentum



Conservation of Momentum
In the absence of external forces the total momentum of a system is always conserved



Impulse
The change in Momentum for a single object
ΔP = Pf - Pi
&
ΔP = FΔt
&
ΔP = mΔv
• The unis are eithor Ns or kgms-1 , this is the same unit and the one that is used depends on the context
• Impulse on one object is always equal and opposite to the impulse on the other onject - Newton's Third Law







Physics of Car Crashes (Impulse)


Impulse


Impulse


Impulse examples///Homemade Science with Bruce Yeany


Impulse


Momentum


What is Momentum?





Impulse

Term 1 Week 7 2020

Homework:

• Ex 4E, p.115-117 Kinematics (earlier week)
• Ex 4F, p.119-124 Projectile Motion (earlier week)
• Ex 4A, p.90-94 Vectors (earlier week)
• Ex 4H, p.132-134, Circular Motion (earlier week)
• Ex 4B, p.97-104 Forces (earlier week)
• Ex 4F, p.143-147 Energy, Work, Power (earlier week)
• Ex 4I, p.137-141, Springs (this week)

PhET - Hooke's Law & Springs - HTML

Hooke's Law

Hooke's Law Introduction - Force of a Spring

Hooke's Law F = -kx

Elastic Potential Energy

Intro to Springs and Hooke's Law

Potential Energy Stored in a Spring

How Hard Can You Hit A Golf Ball?

Term 1 Week 6 2020

Homework:

• Ex 4E, p.115-117 Kinematics (earlier week)
• Ex 4F, p.119-124 Projectile Motion (earlier week)
• Ex 4A, p.90-94 Vectors (earlier week)
• Ex 4H, p.132-134, Circular Motion (earlier week)
• Ex 4B, p.97-104 Forces (earlier week)
• Ex 4F, p.143-147 Energy, Work, Power (this week)

Energy

Energy can never be created

Energy can never be destroyed

Energy can only change its form (Work is done)

Energy has the ability to make something happen, i.e. to do Work

The unit for energy is the Joule (J)

J = Kgm²s-²  in fundamental units

Perpetual Motion Machine?

A Simple Proof of Conservation of Energy

Work, Energy, and Power

Work, Energy and Power Review

Gravitational Potential Energy and Kinetic Energy Skate Park PhET Link - HTML

Work

Work is a transformation (change) of energy from one form to another form. Work only occurs when something is done.

• Power is the rate at which energy is transformed
• Power is the rate at which work is done
• Unit of power Watt (W = J/s)

Power vs Energy

Work, Energy & Power

Kinetic Energy & Gravitational Potential Energy