AP Physics C: Mechanics What is Physics?

Hello, everyone, and welcome to AP Physics C Mechanics here at www.educator.com.0000

I am Dan Fullerton and we are going to start off by talking about what is physics and what we are going to study.0006

Our objectives here in this introduction are going to be to recognize some of the questions of physics.0012

To list several disciplines within the study of physics.0018

To define matter, mass, work, and energy.0021

Let us start off by talking about what is physics and that is kind of a loaded question.0026

The dictionaries say physics relates to matter, energy, and their interactions.0031

But what is matter? What is energy? How they interact? More importantly, why do we care?0036

Physics is the study of everything.0046

I like physics because it answers the questions you get from two year olds all the time -- why?0050

Why is this sky blue? Why does the wind blow? Why does my teacher smell funny?0058

Why do objects fall down instead of up?0062

Would that be cool if they did fall up?0065

I have a list of people as trip and outside every now and then up to the moon.0067

Why do airplanes fly? Why cannot I fly? Why do the stars shine?0072

Why do I have to eat my vegetables?0078

All of these questions are answered by physics in some way or another.0080

Let us start by talking about matter.0086

Matter is anything that has mass and takes up space.0089

You can also think of it as the amount of stuff making up an object.0093

Anything you can touch is matter whether it is stars or electrons are even the kneeled diamond, it is matter.0096

As we talk about matter and mass oftentimes we use them interchangeably.0103

Matter is the stuff.0107

Mass is the amount of stuff making up the object.0108

We are going to talk about two kinds of mass.0111

We are going to talk about inertial mass which is determined by how hard it is to accelerate an object.0114

We are going to be talking about gravitational mass which refers to how large a gravitational force an object experiences.0134

Although they are actually different things any time we have ever tried to measure both of these for a single object0162

they always come out to be exactly the same which is awfully convenient.0167

Inertial mass and gravitational mass are used in different lenses of looking at a problem but they are always the exact same.0172

Let us take a look at an example problem.0183

On the surface of Earth a spacecraft has a mass of 2 times 10⁴ kg.0186

What is the mass of the spacecraft at the distance of 1 Earth radius above Earth's surface?0191

Let see it give us the mass unit and it asks us the mass.0197

If mass is the amount of stuff you are made up of, it is not going to change when you get away from the Earth.0202

You still have the same amount of stuff you made up of so we have the same answer.0208

2 × 10⁴ kg.0212

Let us take a look now at energy.0216

Energy is the ability or capacity to do work.0218

That is not a very helpful definition.0222

Let us talk about work.0224

Work is the process of moving an object if you want to be very informal about it.0226

If we put those together we can say that energy then is the ability or capacity to move an object.0231

We will refine that definition as we move through the course but that is a good starting point for us.0248

Now early 1900s and early 20th century Albert Einstein formalized a relationship between mass and energy0254

that really brought all this stuff together.0262

You have probably seen this formula before E= (mc)².0264

The mass of an object, a key characteristic of matter is actually a measure of the energy contained in an object.0271

There are times when you can convert mass to energy & energy to mass.0278

You can go from one to the other so it is very profound.0283

We also know that the source of all energy on Earth is the conversion of mass and the energy.0287

That is where it originates.0293

Try and think of the form of energy that did not start that way.0295

Physics really then is the study of everything.0299

Try to think of something that is not related to matter and or energy, physics.0303

It is tough to find anything that does not relate to those.0306

Physics is the overarching, the master science, and starting to learn about physics is going to help lead you into a better understanding of the world around you.0312

The study of everything is quite a syllabus for us to take on..0322

We are going to have narrow that down a little bit in this course.0326

What we are going to start with is Mechanics or what we are going to cover our topics like kinematics the study of motion, dynamics, forces.0329

What forces do and how forces cause acceleration and change motions.0339

Work, energy, and power, we will talk about momentum.0344

What happens when moving objects hit other objects?0347

What happens when the objects explode when they collide?0350

We will talk about things that move in circles and things that spin.0354

We will talk about angular momentum.0358

We will talk about the force of gravity.0360

We will talk about oscillations, things that go in cycle, things that repeat in simple harmonic motion.0362

Now there is a bunch of things we are not going to cover but here is just a few that are not covered in the Mechanics part of the course.0369

We are not going to talk about fluids.0374

We are not going to talk about thermodynamics or thermal physics.0376

We are not going to talk about electricity and magnetism.0379

We do have an AP Physics C course on electricity and magnetism here on www.educator.com.0382

We are not going to talk about weight.0388

We are not talk about optics and we are really not going to get much into modern physics.0390

We are going to stick with the classical mechanics with these key topics as highlighted here on the left.0395

As we go into our Mechanics adventure, I would like you to take just a moment and try to write down three things you would like to learn about in physics.0402

List them, put them away somewhere, let us see if you can explain in just a few sentences how matter and energy relate to each of those areas of interest.0411

We are going to see how close you are as we go through and build our understanding of the world around us in AP Physics C Mechanics here at www.educator.com.0419

Thank you so much for your time and joining us on this journey.0427

Make it a great day everyone.0430