Physics

• Physics

• One-dimensional motion
• Two-dimensional motion
• Forces and Newton's Laws of Motion
• Work and energy
• Impacts and linear momentum
• Moments, torque and angular momentum
• Gravitation
• Oscillatory motion
• Fluids
• Thermodynamics
• Electricity and magnetism
• Waves and optics

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One-dimensional motion

 

 

In this tutorial we begin to explore ideas of velocity and acceleration. We do exciting things like throw things off of cliffs (far safer on paper than in real life) and see how high a ball will fly in the air.

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Displacement, velocity and time

This tutorial is the backbone of your understanding of kinematics (i.e., the motion of objects). You might already know that distance = rate x time. This tutorial essentially reviews that idea with a vector lens (we introduce you to vectors here as well). So strap your belts (actually this might not be necessary since we don't plan on decelerating in this tutorial) and prepare for a gentle ride of foundational physics knowledge.

• Introduction to Vectors and Scalars
• Calculating Average Velocity or Speed
• Solving for Time
• Displacement from Time and Velocity Example

Acceleration

In a world full of unbalanced forces (which you learn more about when you study Newton's laws), you will have acceleration (which is the rate in change of velocity). Whether you're thinking about how fast a Porsche can get to 60mph or how long it takes for a passenger plane to get to the necessary speed for flight, this tutorial will help.

• Acceleration
• Airbus A380 Take-off Time
• Airbus A380 Take-off Distance
• Why Distance is Area under Velocity-Time Line

Kinematic formulas and projectile motion

We don't believe in memorizing formulas and neither should you (unless you want to live your life as a shadow of your true potential). This tutorial builds on what we know about displacement, velocity and acceleration to solve problems in kinematics (including projectile motion problems). Along the way, we derive (and re-derive) some of the classic formulas that you might see in your physics book.

• Average Velocity for Constant Acceleration
• Acceleration of Aircraft Carrier Takeoff
• Deriving Displacement as a Function of Time, Acceleration and Initial Velocity
• Plotting Projectile Displacement, Acceleration, and Velocity
• Projectile Height Given Time
• Deriving Max Projectile Displacement Given Time
• Impact Velocity From Given Height
• Viewing g as the value of Earth's Gravitational Field Near the Surface

Old videos on projectile motion

This tutorial has some of the old videos that Sal first did around 2007. This content is covered elsewhere, but some folks like the raw (and masculine) simplicity of these first lessons (Sal added the bit about "masculine").

• Projectile motion (part 1)
• Projectile motion (part 2)
• Projectile motion (part 3)
• Projectile motion (part 4)
• Projectile motion (part 5)

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Two-dimensional motion

 

 

You understand velocity and acceleration well in one-dimension. Now we can explore scenarios that are even more fun. With a little bit of trigonometry (you might want to review your basic trig, especially what sin and cos are), we can think about whether a baseball can clear the "green monster" at Fenway Park.

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Two-dimensional projectile motion

Let's escape from the binds of one-dimension (where we were forced to launch things straight up) and start launching at angles. With a little bit of trig (might want to review sin and cos) we'll be figuring out just how long and far something can travel.

• Visualizing Vectors in 2 Dimensions
• Projectile at an Angle
• Different Way to Determine Time in Air
• Launching and Landing on Different Elevations
• Total Displacement for Projectile
• Total Final Velocity for Projectile
• Correction to Total Final Velocity for Projectile
• Projectile on an Incline
• Unit Vectors and Engineering Notation
• Clearing the Green Monster at Fenway
• Green Monster at Fenway Part 2
• Unit Vector Notation
• Unit Vector Notation (part 2)
• Projectile Motion with Ordered Set Notation

Optimal angle for a projectile

This tutorial tackles a fundamental question when trying to launch things as far as possible (key if you're looking to capture a fort with anything from water balloons to arrows). With a bit of calculus, we'll get to a fairly intuitive answer.

• Optimal angle for a projectile part 1
• Optimal angle for a projectile part 2 - Hangtime
• Optimal angle for a projectile part 3 - Horizontal distance as a function of angle (and speed)
• Optimal angle for a projectile part 4 Finding the optimal angle and distance with a bit of calculus

Centripetal acceleration

Why do things move in circles? Seriously. Why does *anything* ever move in a circle (straight lines seem much more natural). ? Is something moving in a circle at a constant speed accelerating? If so, in what direction? This tutorial will help you get mind around this super-fun topic.

• Race Cars with Constant Speed Around Curve
• Centripetal Force and Acceleration Intuition
• Visual Understanding of Centripetal Acceleration Formula
• Calculus proof of centripetal acceleration formula
• Loop De Loop Question
• Loop De Loop Answer part 1
• Loop De Loop Answer part 2

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Forces and Newton's Laws of Motion

 

 

 

This tutorial is the meat of much of classical physics. We think about what a force is and how Newton changed the world's (and possibly your) view of how reality works.

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Newton's laws of motion

This tutorial will expose you to the foundation of classical mechanics--Newton's laws. On one level they are intuitive, on another lever they are completely counter-intuitive. Challenge your take on reality and watch this tutorial. There world will look very different after you're done.

• Newton's First Law of Motion
• Newton's First Law of Motion Concepts
• Newton's First Law of Motion
• Newton's Second Law of Motion
• Newton's Third Law of Motion

Normal force and contact force

A dog is balancing on one arm on my head. Is my head applying a force to the dog's hand? If it weren't, wouldn't there be nothing to offset the pull of gravity causing the acrobatic dog to fall? What would we call this force? Can we have a general term from the component of a contact force that acts perpendicular to the plane of contact? These are absolutely normal questions to ask.

• Normal Force and Contact Force
• Normal Force in an Elevator

Balanced and unbalanced forces

You will often hear physics professors be careful to say "net force" or "unbalanced force" rather than just "force". Why? This tutorial explains why and might give you more intuition about Newton's laws in the process.

• Balanced and Unbalanced Forces
• Unbalanced Forces and Motion

Slow sock on Lubricon VI

This short tutorial will have you dealing with orbiting frozen socks in order to understand whether you understand Newton's Laws. We also quiz you a bit during the videos just to make sure that you aren't daydreaming about what you would do with a frozen sock.

• Slow Sock on Lubricon VI
• Normal Forces on Lubricon VI

Inclined planes and friction

We've all slid down slides/snow-or-mud-covered-hills/railings at some point in our life (if not, you haven't really lived) and noticed that the smoother the surface the more we would accelerate (try to slide down a non-snow-or-mud-covered hill). This tutorial looks into this in some depth. We'll look at masses on inclined planes and think about static and kinetic friction.

• Inclined Plane Force Components
• Ice Accelerating Down an Incline
• Force of Friction Keeping the Block Stationary
• Correction to Force of Friction Keeping the Block Stationary
• Force of Friction Keeping Velocity Constant
• Intuition on Static and Kinetic Friction Comparisons
• Static and Kinetic Friction Example

Tension

Bad commute? Baby crying? Bills to pay? Looking to take a bath with some Calgon (do a search on YouTube for context) to ease your tension? This tutorial has nothing (actually little, not nothing) to do with that. So far, most of the forces we've been dealing with are forces of "pushing"--contact forces at the macro level because of atoms not wanting to get to close at the micro level. Now we'll deal with "pulling" force or tension (at a micro level this is the force of attraction between bonded atoms).

• Introduction to Tension
• Introduction to Tension (Part 2)
• Tension in an accelerating system and pie in the face

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Work and energy

 

 

 

 

Work and energy. Potential energy. Kinetic energy. Mechanical advantage. Springs and Hooke's law.

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Work and energy

You're doing a lot more work than you realize (most of which goes unpaid). This tutorial will have you seeing the world in terms of potentials and energy and work (which is more fun than you can possibly imagine).

• Introduction to work and energy
• Work and Energy (part 2)
• Conservation of Energy
• Work/Energy problem with Friction

Mechanical advantage

If you have every used a tool of any kind (including the bones in your body), you have employed mechanical advantage. Whether you used an incline plane to drag something off of a pick-up truck or the back of a hammer to remove a nail, the world of mechanical advantage surrounds us.

• Introduction to mechanical advantage
• Mechanical Advantage (part 2)
• Mechanical Advantage (part 3)

Springs and Hooke's Law

Weighing machines of all sorts employ springs that take a certain amount of force to keep compressed or stretched to a certain point. Hooke's law will give us all the tools to weigh in on the subject ourselves and spring into action (yes, the puns are annoying us too)!

• Intro to springs and Hooke's Law
• Potential energy stored in a spring
• Spring potential energy example (mistake in math)

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Impacts and linear momentum

 

 

 

Linear momentum. Conservation of momentum. Elastic collisions.

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Momentum

Depending on your view of things, this may be the most violent of our tutorials. Things will crash and collide. We'll learn about momentum and how it is transferred. Whether you're playing pool (or "billiards") or deciding whether you want to get tackled by the 300lb. guy, this tutorial is of key importance.

• Introduction to Momentum
• Momentum: Ice skater throws a ball
• 2-dimensional momentum problem
• 2-dimensional momentum problem (part 2)

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Moments, torque and angular momentum

 

 

 

Thinking about making things rotate. Center of mass, torque, moments and angular velocity.

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Torque, moments and angular momentum

Until this tutorial, we have been completely ignoring that things rotate. In this tutorial, we'll explore why they rotate and how they do it. It will leave your head spinning (no, it won't, but seemed like a fun thing to say given the subject matter).

• Center of Mass
• Introduction to Torque
• Moments
• Moments (part 2)
• Relationship between angular velocity and speed
• Conservation of angular momentum

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Gravitation

 

 

 

Classical gravity. How masses attract each other (according to Newton).

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Newton's law of gravitation

Why are you sticking to your chair (ignoring the spilled glue)? Why does the earth orbit the sun (or does it)? How high could I throw my dog on the moon? Gravitation defines our everyday life and the structure of the universe. This tutorial will introduce it to you in the Newtonian sense.

• Introduction to Gravity
• Mass and Weight Clarification
• Gravity for Astronauts in Orbit
• Would a Brick or Feather Fall Faster
• Acceleration Due to Gravity at the Space Station
• Space Station Speed in Orbit
• Introduction to Newton's Law of Gravitation
• Gravitation (part 2)

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Oscillatory motion

 

 

 

Pendulums. Slinkies. You when you have to use the bathroom but it is occupied. These all go back and forth over and over and over again. This tutorial explores this type of motion.

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Harmonic motion

Every watch a slinky gyrate back and forth. This is harmonic motion (a special class of oscillatory motion). In this tutorial we'll see how we can model and deal with this type of phenomena.

• Introduction to Harmonic Motion
• Harmonic Motion Part 2 (calculus)
• Harmonic Motion Part 3 (no calculus)

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Fluids

 

 

 

1. Fluids (part 1)
2. Fluids (part 2)
3. Fluids (part 3)
4. Fluids (part 4)
5. Fluids (part 5)
6. Fluids (part 6)

1. Fluids (part 7)
2. Fluids (part 8)
3. Fluids (part 9)
4. Fluids (part 10)
5. Fluids (part 11)
6. Fluids (part 12)

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Thermodynamics

 

 

 

 

1. Thermodynamics (part 1)
2. Thermodynamics (part 2)
3. Thermodynamics (part 3)
4. Thermodynamics (part 4)
5. Thermodynamics (part 5)
6. Macrostates and Microstates
7. Quasistatic and Reversible Processes
8. First Law of Thermodynamics/ Internal Energy
9. More on Internal Energy
10. Work from Expansion
11. PV-diagrams and Expansion Work
12. Proof: U=(3/2)PV or U=(3/2)nRT
13. Work Done by Isothermic Process
14. Carnot Cycle and Carnot Engine
15. Proof: Volume Ratios in a Carnot Cycle
16. Proof: S (or Entropy) is a valid state variable
17. Thermodynamic Entropy Definition Clarification
18. Reconciling Thermodynamic and State Definitions of Entropy
19. Entropy Intuition
20. Maxwell's Demon

1. More on Entropy
2. Efficiency of a Carnot Engine
3. Carnot Efficiency 2: Reversing the Cycle
4. Carnot Efficiency 3: Proving that it is the most efficient
5. Enthalpy
6. Heat of Formation
7. Hess's Law and Reaction Enthalpy Change
8. Gibbs Free Energy and Spontaneity
9. Gibbs Free Energy Example
10. More rigorous Gibbs Free Energy/ Spontaneity Relationship
11. A look at a seductive but wrong Gibbs/Spontaneity Proof
12. Stoichiometry Example Problem 1
13. Stoichiometry Example Problem 2
14. Limiting Reactant Example Problem 1
15. Empirical and Molecular Formulas from Stoichiometry
16. Example of Finding Reactant Empirical Formula
17. Stoichiometry of a Reaction in Solution
18. Another Stoichiometry Example in a Solution
19. Molecular and Empirical Forumlas from Percent Composition
20. Hess's Law Example

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Electricity and magnetism

 

 

 

 

1. Electrostatics (part 1): Introduction to Charge and Coulomb's Law
2. Electrostatics (part 2)
3. Proof (Advanced): Field from infinite plate (part 1)
4. Proof (Advanced): Field from infinite plate (part 2)
5. Electric Potential Energy
6. Electric Potential Energy (part 2-- involves calculus)
7. Voltage
8. Capacitance
9. Circuits (part 1)
10. Circuits (part 2)
11. Circuits (part 3)
12. Circuits (part 4)
13. Cross product 1
14. Cross Product 2
15. Cross Product and Torque

1. Introduction to Magnetism
2. Magnetism 2
3. Magnetism 3
4. Magnetism 4
5. Magnetism 5
6. Magnetism 6: Magnetic field due to current
7. Magnetism 7
8. Magnetism 8
9. Magnetism 9: Electric Motors
10. Magnetism 10: Electric Motors
11. Magnetism 11: Electric Motors
12. Magnetism 12: Induced Current in a Wire
13. The dot product
14. Dot vs. Cross Product
15. Calculating dot and cross products with unit vector notation

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Waves and optics

 

 

 

 

1. Introduction to Waves
2. Amplitude, Period, Frequency and Wavelength of Periodic Waves
3. Introduction to the Doppler Effect
4. Doppler effect formula when source is moving away
5. When the source and the wave move at the same velocity
6. Mach Numbers
7. Specular and Diffuse Reflection
8. Specular and Diffuse Reflection 2
9. Refraction and Snell's Law
10. Refraction in Water
11. Snell's Law Example 1
12. Snell's Law Example 2

1. Total Internal Reflection
2. Virtual Image
3. Parabolic Mirrors and Real Images
4. Parabolic Mirrors 2
5. Convex Parabolic Mirrors
6. Convex Lenses
7. Convex Lens Examples
8. Doppler effect formula for observed frequency
9. Concave Lenses
10. Object Image and Focal Distance Relationship (Proof of Formula)
11. Object Image Height and Distance Relationship