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Course: AP®︎/College Physics 1 > Unit 1
Lesson 1: AP Physics 1 foundationsWhat is physics?
Let's think about what physics is and what topics are covered in AP Physics 1.
What is physics?
To be honest, it’s really difficult to define exactly what physics is. For one, physics keeps changing as we progress and make new discoveries. New theories don't just bring new answers. They also create new questions that might not have even made sense when viewed from within the previous theory of physics. This makes physics exciting and interesting, but it also forces attempts at defining physics into generalizations about what physics has been rather than what it might be at some point in the future.
That said, definitions are useful. So, if it’s a definition you want, it’s a definition you’ll get. For the most part, physicists are trying to do the following:
- Precisely define the most fundamental measurable quantities in the universe (e.g., velocity, electric field, kinetic energy). The effort to find the most fundamental description of the universe is a quest that has historically always been a big part of physics, as can be seen in the comic image below.
- Find relationships between those fundamental measured quantities (e.g., Newton’s Laws, conservation of energy, special relativity). These patterns and correlations are expressed using words, equations, graphs, charts, diagrams, models, and any other means that allow us to express a relationship in a way that we as humans can better understand and use.
Image credit: Adventures Inside the Atom, 1948 General Electric, George Roussos (public domain)
OK, so boiling physics down to only two things is admittedly a bit of a gross simplification and glosses over some of the finer points of what physicists do and how they do it. But trying to describe a complex universe with simple and useful clarifying laws is what physics is all about. So maybe trying to describe the complex activity of what physicists do with a simple and clarifying definition isn’t such a bad idea after all.
What will I learn by studying physics on Khan Academy?
In physics, we want to explain why objects move around the way they do. However, it would be hard to explain motion if we didn't know how to describe motion. So first, in the topics One-dimensional motion and Two-dimensional motion, we'll learn how to precisely describe the motion of objects and predict their motion for some special cases.
With the ability to precisely describe motion under our belt, we'll learn in Forces and Newton's Laws how the concept of force allows us to explain why objects change their motion.
We'll continue mastering and expanding our ability to deal with motion by showing that conservation laws are an alternative way to explain the motion of an object. These conservation laws give constraints on how the motion of a system can change. Conservation of energy will be learned in Work and energy, and conservation of momentum will be learned in Linear momentum and collisions.
Up to that point we'll have mostly considered objects that are not changing their rotational motion, so in Rotational motion and torque we'll learn how to describe and explain rotational motion and pick up a new conservation law along the way—conservation of angular momentum.
After this point, we'll deploy what we learned about motion, forces, and conservation laws to analyze how to deal with a variety of new forces and phenomena. In Simple harmonic motion and Waves and sound we'll Iearn what water waves and woodwind instruments have in common. We'll explore a new force—the electric force—in Electric charge and electric force. In DC circuits we'll see how electric forces cause current to flow.
By the end you should have a nice understanding of introductory physics and the mathematical tools physicists use to describe and explain the universe. But no summary can describe all the interesting and powerful aspects of physics. The best way to find out is to jump in and see for yourself.
Want to join the conversation?
- Is angular momentum the only quantity that has rotational motion? In other words, is angular momentum the only tool used to measure rotational motion?
If the above is not true, then are kinetic energy and momentum also ways to measure rotational motion?
What is the relationship between Torque and rotational motion? I'm asking that question because i noticed them grouped together.(18 votes)- No, angular momentum is just one of many quantities we can use to determine and predict how something moves in a circular motion. All ideas of motion in a line have a counterpart for circular motion. Force --> Torque. Speed --> Angular Velocity. Acceleration --> Angular Acceleration. We also have things that exist in circular motion that do not in angular motion. For instance, Centrifugal Force is a force we FEEL that pushes us to the outside of a turn when I turn a car sharply around a corner.(10 votes)
- does physics work on everything?(1 vote)
- Everything that exists within our universe. Everything follows the laws of physics anything that defies them is following rules we don't understand(14 votes)
- Is physics important in life?(4 votes)
- yes, physics helps us establish why certain phenomenon occur in nature and others don't, it helps us to control these phenomenon and make our life simpler, by applying these basic principles in the machines that we use in our day to day life, to invent them and to make the existing machines more efficient(6 votes)
- I am going into my senior year and have chosen AP Physics. The weird thing is that my school does not specify whether is AP Physics 1 or 2. I have no prior experience with Physics as I was on the chemistry route throughout high school. Should I watch the normal Physics videos or the AP Physics 1 videos? I glanced at it and saw that they cover different things.(6 votes)
- Maybe try AP Physics 1 because it's pretty basic and you can build up from there.(1 vote)
- Why do we study physics?(3 votes)
- To understand the workings of the universe from the most tiny to the absolutely largest imaginable level. To explain all the phenomena we know to exist at a fundamental or very basic level. To explain why there even is a universe to explain in the first place... Well, maybe that lies beyond the possibilities of science, but physics will still try to provide an answer to that question.(2 votes)
- How old do we have to be to start physics?(2 votes)
- what is the diffrent between scalar and vector quantities(2 votes)
- why do i need physics if i want to be an robotic engineer?(2 votes)
- what is the difference between scalar and vector quantities? I am very confused.(1 vote)
- A vector is a quantity that has both direction and magnitude. For example force is a vector because it has a magnitude and a direction in which it is exerted. A scalar is a quantity that has only a magnitude. For example, energy is a scalar because you can only gain or lose it. It does not actually have a direction.(2 votes)
- Why is everything the way it is?(1 vote)
- I guess those are the questions that we like to probe and try to build our understanding to assist with that. Its still ongoing, and that's part of its beauty.
For starters though, for an interesting perspective, you could read up on 'The Anthropic principle', both 'strong' and 'weak' versions. Fascinating.
Hope that helps!(1 vote)