Static Friction and some friction challenges | Doc Physics

Here, I talk about sneaky ol' static friction.

[lahockeyboy]

Doc...you rock!!! Thanks for all the terrific lessons!

[DocSchuster]

Thanks, man! You've made my day!

[Kravch]

you know you are an awesome teacher when you use a dead cat to explain things

[hrishikeshdalvi]

Kinetic friction in the forward direction and static friction in backward

[ZackNicholas]

Wow, and my professor told me the derivative of acceleration was a jerk. Turns out it was friction the whole time!

[DocSchuster]

Thanks, Kirill. I like to teach with whatever's on hand. If the cat's nearby, use it!

[laurencolbeck]

i would say its static friction as your walking (as long as your feet are not sliding in which case i would say its kinetic friction) just because your feet dont slide they stay static and push you forward? 

[DocSchuster]

Well, I think I need more detail. Whatcha got?

[Mayflower]

Because feet on ground is not sliding across ground but remaining still, this is static friction. That static friction pushes us in any direction.

[rivkafranklin]

I wish you would answer the questions in your video, because I don't see replies or video responses to them and I would like to know the correct answer. Thanks. 

[varun]

Sorry to bother you, but I have to design an experiment (which I don't have to perform) for my HL physics class and I wanted to ask you some questions. The experiment deals with correlating the surface area of a simple, dome shaped parachute canopy on its rate of descent. All things being equal (air density, canopy geometry... ect.) I think that the final rate of descent will be determined by the time taken for the parachute to reach terminal velocity and its velocity at that instant. With that in mind I have also told my teacher that, since surface area and force are both factors, pressure must be considered too. I hypothesize that, since drag force is always equal to mg in the absence of air flow, pressure would be greater for canopies with smaller surface areas and would, therefore, take longer to reach terminal velocity and would travel faster. can you comment on this?

[quadcatfly]

Was a cat dead or alive !? Uncertain !

[antidowt]

7:35 i just moved a tree :)! Are you with me?