Correction of definition of "normal force" and an introduction to the coefficient of friction. This video, which is suitable for high school students, starts with a black screen because the instructor, in his conversational tone, uses it as a 'chalkb...oard.' (09:25)[more]

Calculating the acceleration of on object sliding down an inclined plane with friction. This ten-minute video, which is suitable for high school students, starts with a black screen because the instructor, in his conversational tone, uses it as a 'ch...alkboard.'[more]

Fun with two masses, some wire, a pulley, and a ramp with friction. This video, which is suitable for high school students, starts with a black screen because the instructor, in his conversational tone, uses it as a 'chalkboard.' (10:15)

This is how you include air resistance in projectile motion. It requires the Drag Force and Numerical Modeling (or the Euler Method). It is also very helpful to use a spreadsheet to do the calculations. I prove a statement from a previous projecti...le motion problem video, "Air resistance decreases the x displacement of the ball by less than 1 cm."
Content Times:
0:22 The statement this video proves
1:01 The basic concept of air resistance
1:54 The Free Body Diagram
2:20 The Drag Force Equation
3:13 Information about the Lacrosse Ball
4:03 The Drag Coefficient
4:55 The Density of Air
5:18 How the Drag Force affects the motion
5:58 The basic idea of Numerical Modeling (or the Euler Method)
6:50 Solving for the acceleration in the x direction
8:53 Solving for the final velocity in the x direction
9:54 Solving for the final position in the x direction
11:41 Entering the Lacrosse Ball information into Excel
13:34 Solving for the Drag Force in x direction in Excel
14:29 Solving for the acceleration in the x direction in Excel
14:58 Solving for the final velocity and final position in the x direction in Excel
15:46 Solving for the acceleration in the y direction
17:21 Solving for all the variables in the y direction in Excel
19:13 Click and Drag Copy. Harnessing the Power of Excel!
19:43 Understanding the numbers in Excel
20:35 Solving for the decrease in the x displacement caused by the Drag Force
Want lecture notes & the Excel File?
The original problem videos for this are:
(part 1 of 2) An Introductory Projectile Motion Problem with an Initial Horizontal Velocity
(part 2 of 2) An Introductory Projectile Motion Problem with an Initial Horizontal Velocity
How Many Attempts did it Really Take? - with live music from Amos Lee
Next Problem: Nerd-A-Pult – An Introductory Projectile Motion Problem
1¢/minute[more]

Determine if the book moves or not and the acceleration of the book. It’s all about static and kinetic friction.
Want Lecture Notes? This is an AP Physics 1 topic.
Content Times:
0:08 Reading and translating the problem
0:57 5 Steps to help solv...e any Free Body Diagram problem
1:26 Drawing the Free Body Diagram
2:24 Sum the forces in the y-direction
3:22 Sum the forces in the x-direction
4:56 The answer to part (a)
6:22 Solving part (b)
Next Video: Everybody Brought Mass to the Party!
Multilingual? Please help translate Flipping Physics videos!
Previous Video: Experimentally Graphing the Force of Friction
1¢/minute[more]

To help understand the force of friction, mr.p pulls on a wooden block using a force sensor. Want Lecture Notes?
This is an AP Physics 1 topic.
Content Times:
0:17 Drawing the Free Body Diagram
0:43 Summing the forces in the x-direction
1:21 Gr...aph when the block doesn’t move
1:46 Graph with the block moving
Next Video: Does the Book Move? An Introductory Friction Problem
Multilingual? Please help translate Flipping Physics videos!
Previous Video: Understanding the Force of Friction Equation
1¢/minute[more]

The Force of Friction Equation is actually three equations is one. Learn why! Want Lecture Notes? This is an AP Physics 1 topic.
Content Times:
0:00 The basic Force of Friction Equation
0:20 One Kinetic Friction Equation
0:39 The Two Static Fric...tion Equations
1:40 Example Free Body Diagram
2:16 The direction of the Force of Friction
3:20 Determining the magnitude of the Force of Static Friction
4:09 Understanding the “less than or equal” sign
6:08 If the “less than or equal” sign were not there
Next Video: Experimentally Graphing the Force of Friction
Multilingual? Please help translate Flipping Physics videos!
Previous Video: Introduction to the Coefficient of Friction
1¢/minute[more]

If you hold your feet flat or point them, does it change how far you slide. This video shows the answer and explains why using the concept of drag force.
Content Times:
0:26 Showing the two foot positions
0:57 Defining aerodynamic
1:41 Defining... the Drag Force
2:32 A closer look at the cross sectional area
4:04 Showing the answer
5:05 Comparing splashes
5:43 A second demonstration
6:22 Many thanks
Multilingual? Please help translate Flipping Physics videos!
Another Drag Force Video: A Brief Look at the Force of Drag using Numerical Modeling (or The Euler Method)
Thank you Rhonda Petty of Rolling Hills Water Park
Thank you Aaron Fown of FirstUAV for the aerial footage.
1¢/minute[more]

Bobby teaches the basics of friction and the differences between Static and Kinetic Friction. Want Lecture Notes?
This is an AP Physics 1 topic.
Content Times:
0:11 Basic definition of friction
0:40 What causes friction?
1:30 Static and kinetic... friction demonstrated
2:10 Friction is independent of surface area
2:47 The direction of the force of friction
Multilingual? Please help translate Flipping Physics videos!
Next Video: Introduction to the Coefficient of Friction
Previous Video: An Introductory Tension Force Problem
1¢/minute[more]

Please make your comments on categories positive, and not just negative.

People work hard on educational categories, and we want to encourage them to make more!

Profanity (curse words), sexually suggestive remarks, and other such obviously inappropriate comments
will be deleted immediately, and are grounds for immediate expulsion. Remember, children use this website.

Personal criticism on project forums and in video content is not allowed and will be deleted immediately.
Any violations of this rule could result in expulsion from the project so please, no insults or other negative
personal remarks.

Very harshly-worded criticism of content will also be deleted promptly. Please use your vote to express your
harshest feelings. Repeated violations of this rule can result in expulsion. If you must criticize another
person's hard work, then be nice about it.

People work hard on educational categories, and we want to encourage them to make more!