BlogLearnGuide to Year 11 Physics Module 2: Dynamics

# Guide to Year 11 Physics Module 2: Dynamics

Just starting Year 11 Physics Syllabus Module 2: Dynamics?

As you settle in to the sometimes-wacky world that is thinking like a Physicist, our comprehensive guide to Year 11 Physics Module 2: Dynamics will help you become a Physics force to be reckoned with.

The new Module 1 Kinematics made a point of throwing students a bit in the deep-end, to get some heavy-lifting out of the way and important recurring skills nailed down early on.

If you need some help with Year 11 Physics Module 1: Kinematics, check out our guide here!

Breaking through to Module 2, you’ve already laid solid groundwork behind the skills/tools and logic of physics problems solving. Through Module 2, you’ll notice a familiar pattern developing in how to successfully attack problems!

In this article, we’ll cover how to prepare, use class time and smash through Year 11 Physics Module 2: Dynamics on the journey towards your Band 6!

### What is Dynamics all about?

Kinematics describes the states of motion we witness objects in. You developed a stack of tools for this, like vector addition of velocities and displacements.

Dynamics analyses the coming together of forces (push/pulls – also vectors).

Their combined action can work to bring about changes in motion; or conspire to make sure that motion stays unchanged (including constantly no motion, or any other motion status quo).

In other words, dynamics studies the reasons underneath all the types of motion (changing and unchanging) studied in Module 1: Kinematics.

This time, your toolbox is vector addition of forces (married to Newton’s 3 Laws).

You’ve already met acceleration (without its cause). You’ll be adding words like momentum, inertia and energy to this description of unbalanced force response.

### Breakdown of Physics Module 2: Dynamics

There are three main ‘Inquiry Questions’ for Year 11 Physics Module 2: Dynamics:

Inquiry Question 1: How are forces produced between objects and what effects do forces produce?

Inquiry Question 2: Inquiry question: How can the motion of objects be explained and analysed?

Inquiry Question 3: How is the motion of objects in a simple system dependent on the interaction between the objects?

Are you thinking this module sounds like the old module Moving About? It’s similar, but expanded upon.

Syllabus commands like “identify” and “describe” are out; things like “evaluate” and “’analyse” have taken over.

Your vector addition skills, practiced in Kinematics, are going to come out refined, but red-hot from overuse.

The module starts out by laying down Newton’s Laws (Inquiry Question 1). The rest of the module trains you to make skilled application of them to complex situations.

You’ll be analysing force vectors in real-world static and accelerated motion situations (in 2D), guided by Newton and solving for things like rope tensions and road frictions (Inquiry Question 2)

Later, you’ll look at how unbalanced force leads to energy and momentum changes (through velocity change); and the resulting details of collisions in 2D (momentum vectors) that fall out of Newton’s Laws (Inquiry Question 3).

This proper treatment of the vectors and maths of physics extends from Module 1 and gives a stronger foundation for Year 12 and university-level Physics/Maths/Engineering.

## How to get a Band 6 in Physics Module 2: Dynamics

Here’s a breakdown of the knowledge and understanding this module targets for mastery development:

Dynamics begs you to become expert in three areas:

1. Applying Newton’s Laws to Force vector addition in 2D

2. How net force changes energy (with displacement) and momentum (with time)

3. Applying Momentum Conservation (from Newton) to collisions in 2D (vector addition)

### Firstly, identify your misconceptions of Newton’s Laws and mark them for demolition.

Everyone brings aboard a suite of totally natural misconceptions, when they embark on Module 2. It’s probably *the* most misconception-blocked Physics topic.

You’ve had a lifetime of pushing objects around to arrive with assumptions that work well if you want to throw a ball to someone here on Earth.

But how do you know what effect your hand really has on the ball, if gravity and air are always getting in the way changing the results?

Here’s what research finds are the most common Newton’s Laws misconceptions:

Misconception: Sustained motion needs sustained force (implying motion “dissipates”)

Truth: Unbalanced force is needed to alter motion.

Misconception: There is no motion without force

Truth: There is no change in motion without unbalanced force.

Misconception: Equal and/or opposite reactions “cancel each other out”.

Truth: When A pushes B, B pushes back on A just as hard (something can only receive a push by pushing off something else – these are forces on different bodies always)

Misconception: Heavier objects fall faster.

Truth: Everything falls identically by gravity (hard-to-move objects are pulled harder).

Misconception: Inertia keeps things moving but doesn’t make it hard to start things moving.

Truth: Inertia (mass) measures resistance/sensitivity to any change in motion.

Unlearning these to make way for the truth will take some effort!

If you don’t have access to a lot of “frictionless/airless” environments (not many of us do…) to really see the force-machinery under the hood, there’s a tonne of interactive simulators online that let you push things around and watch the motion change!

A great site to experiment with is this one from PhET University of Colorado!

#### PhET Simulator – University of Colorado

Secondly, get used to your new world view being defined by Newton’s Laws.

This step’s a bit harder… You need to try and develop a “feel” or intuition for Newton’s Laws.

The best way to do this is to obsess over Newton’s Laws.

• When you’re walking; when you’re driving; when you’re playing sport – convince yourself shoes and tires are designed to maximally grip the Earth and throw it backwards.
• Convince yourself balls stop rolling because the ground pulls them back.
• Convince yourself plane rides feel identical to sitting motionlessly in a chair on the ground (no net force) except when the plane is changing its motion.
• Convince yourself rockets push off gases (and do so all the way up!).
• Convince yourself the cannon and cannonball are equally pushed apart, but the heavier cannon is less force-sensitive (higher mass).
• Convince yourself swinging a golf club exactly as hard at a bowling ball is less effective.
• Convince yourself gravity pulls heavier things harder to make them fall the same (how hard would you have to swing at the bowling ball to make it fly the same as a golfball?!).
• Convince yourself you need to touch the accelerator to cover up road friction and produce a no-net-force situation to maintain unchanging speed when you drive. Convince yourself rolling balls slow down because they can’t do exactly this!

View the world through the lens of Newton when you’re walking to school or doing anything – convince yourself of the reality of your replaced misconceptions.

##### Here’s your very own intuition checklist!

This checklist outlines the ideas and concepts to keep in mind when you’re thinking about Newton’s Laws and how they operate in reality:

1. Any force exerted on any object is always exerted by another object.
2. Whenever one object exerts a force on a second object, the second object exerts an equal force in the opposite direction on the first. (When something pushes something else, it gets pushed back just as hard.)
3. Action-reaction pairs always act on different bodies. They cannot cancel each other, as only forces acting on the same object can cancel.
4. The resulting accelerations of the objects (under equal force) is controlled by their masses (their inertia).
5. The resulting acceleration is proportional to the amount of unbalanced force acting, and the objects “lightness” (force sensitivity; the force is divided up over less mass)

### Step 2: Use Prescribed Strategy for Problem Solving

Firstly, start practicing Newton’s Law Force diagrams!

This is something you become skilled at with practice. Deliberately burn through as many practice questions as you can get your hands on.

Fall off the bike the exact required number of times that stand between you and that moment where you go “Woah, I’m doing it! I can do this!”

For everyone, in this topic, that number requires some determination!

To make this easier, we’ve outlined exactly how to do it below:

#### Use this one to solve Force situations:

1. Sketch the scenario in full.
2. Re-sketch objects individually (free-body diagram), showing all the forces acting on that object as labelled vectors (whose length and direction are as accurate as possible). Don’t show forces that the chosen object exerts on other objects to put force on itself (the full action-reaction partners)

Label vectors clearly identifying the actor and acted-upon e.g. for Force A exerts on B, write

1. is a vector sum; it’s usually helpful to resolve vectors into components and sum them along (x and y) axes. Choose one axis along the direction of acceleration (or zero acceleration). Pick a direction in this axis to call positive and stick to it.
2. For each object, write a true Net Force/Newton’s Law Statement in the x anddirections separately: i.e. and  equal either max, may or zero. These components can reform a resultant ΣF vector later.

#### Use this one to solve Conserved Momentum (1D  + 2D collision) situations:

1. Sketch the scenario in full
2. Decompose velocity vectors along axes of interest (x and y i.e. axes with no pre-collision momenta, and all of it)
3. Write a true Momentum Conservation statement along each axis separately. i.e. pfinalx = pinitalx and pfinaly = pinitaly
4. Bring your above x-momentum and y-momentum statements together to solve.

And practice, practice, practice until it starts becoming effortless! (Everyone has to concentrate hard when they first ride a bike – afterwards, it’s more automatic!)

### Step 3: Recast the role of class-time in your life

Because the syllabus is more internationally aligned, there are riches of resources out there already, beyond your prescribed text, that can be used to throw yourself into the content ahead of your class.

This recasts your class time in the role of a revision session with an expert consultant (teacher), ready to answer your pre-formed questions.

## How to Prepare for Year 11 Physics Module 2: Dynamics

### Step 1: Gather your resources

Use online learning to launch yourself at least a week ahead of your class and pre-learn the concepts. Bring already-identified sticking points to your class lessons. Be proactive!

Crunch through as many questions as it takes to feel confident (present challenging ones to your tutor and teacher to make the solving strategies known to you).

### Step 2: Rewrite your Newton’s Laws misconceptions

Make a concerted effort to roll back your earthbound preconceptions, to be replaced with the updated truth.

This is an important skill not only for Physics, but for all sciences and life in general…

Keep Newton’s Laws in the back of your mind outside of class and convince yourself of what forces really do – and that your rewritten conceptions are indeed truth. Develop a familiarity and feel for Newton’s Laws. Notice how they work as you move through everyday life.

### Step 3: Use your notes as a gap-identifying tool

Rewrite your class notes as if you had to explain the concepts to someone with no knowledge of Physics. Translate your notes from textbook-speak to familiar, everyday terms.

If you’re having trouble formulating a way to teach the concept to a non-scientist, you’ve just ID’d an area you don’t understand as deeply as you first thought! Run to your textbook/online to further develop a way to explain the underlying idea in simple terms!

### Step 4: Hone your problem-solving skills

Most of this course is mastered through polishing the unique, unfamiliar problem-solving skills Physics questions require. A whole host of solving strategies are not obvious, and just a matter of having seen them.

You’ll get accustomed to the common ways certain problems (like force diagrams, or collisions) are solved by making the strategies known to yourself (by failing to solve a question then seeking the solution!) and practicing their application.

Never feel incapable because the way was not immediately clear. Worked solutions will often need consulting first, as Physics is a wholly new way of thinking!

## On the hunt for other Year 11 Physics resources?

Check out the other module breakdowns we’ve created for Year 11 Physics below:

## Are you looking for some extra help with Year 11 Physics Module 2: Dynamics?

#### We pride ourselves on our inspirational Year 11 Physics coaches and mentors!

We offer tutoring and mentoring for Years K-12 in a large variety of subjects, with personalised lessons conducted one-on-one in your home or at our state of the art campus in Hornsby!

To find out more and get started with an inspirational tutor and mentor get in touch today!

Give us a ring on 1300 267 888, email us at [email protected] or check us out on Facebook!

Adrian Wendeborn is a qualified Science and Maths teacher with a Physics/Chemistry double-major degree from USYD and a GDipEd from UQ. Adrian has taught in QLD and NSW and has worked with Art of Smart Education as a campus teacher, tutor, resource developer and Head of Faculty.

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