AP Physics 1: Forces 12: Static and Kinetic Friction

[@lananhle3761]

Very organized . Excellent demonstration and explanation. Thank you.

[@AK-gt8zy]

Thanks so much! You are very organized with your thoughts and that helped me understand the topic :)

[@onlearningcurve]

Thanks : )

[@MichelleZhou]

Thank you so much for existing!

[@limribing3020]

Thanks for the pulling demonstration , I can imagine for the graph already!!

[@iirazor1086]

Thank you, you did a much better job then my physics teacher at explaining this

[@tsunadegirl1]

I looked at the book and cringed. That's the same book we use in my high school physics class, the one my teacher says not to use. This video helped a lot, thank you.

[@onlearningcurve]

I agree with you and your teacher - this 6th edition Giancoli is not good for AP Physics 1 and 2. We just have to make do with it until our district let's us get new books.

[@ashleyr2014r]

I love you twu!!!

[@alexanderesparza4667]

Very helpful video, thank you!

[@maryamhaeri1215]

thank you so much! this video was very helpful.

[@xKiDDiamonDx]

great teacher really appreciate it.

[@theroyalosha]

Thank u very much. I really understand

[@everythinkyouthink2381]

mam you are god....thankyou

[@nishanxerox9435]

thanks mam i understood it in a clear way

[@salatshahid3752]

nice ... but i didnt understand why friction at last is stable /: eventhough pressure is increasing and the surface is changing

[@autumnpaul3123]

Genius :) thank you so much!!

[@brandon1121]

Extremely helpful.

[@anzatzi]

In frictionless case--isn't there force needed to accelerate the book?

[@anikaitsingh8174]

Thank you. A very nice video.

[@Sandysan11111]

Why is the max static is higher than the k friction?

[@onlearningcurve]

Imagine the book and the table with bumpy surfaces. I think it may be because the two contact surfaces can be a bit closer to each other when the book is sitting on the table than when the book is sliding on the table.

[@gizmo928]

5kg = 50 newtons??

[@onlearningcurve]

An object with 5kg of mass weighs about 50 newtons near the surface of the Earth. However, we do not write 5kg = 50N, because mass and weight are 2 different kinds of things. Mass is, well, mass, but weight is a force. Weight is the gravitational pull an object experiences from the planet (or similar things).

[@physicsworld9301]

epic

[@salatshahid3752]

nice ... but i didnt understand why friction at last is stable /: eventhough pressure is increasing and the surface is changing

[@onlearningcurve]

+SALAT SHAHID You are right to wonder about the surface condition change. Friction can be tricky. It's tricky when I set up things for the demonstration too. If I push the block down hard and then let go before pulling on it, it would likely require a bigger force to get block to move. Pushing the block down really hard makes the 2 contact surfaces a bit closer, so in a way, the contact surface condition is changed. So in order to make the demonstration more consistent, I had to make sure that the block was placed on the table gently before I started to pull on it. Once the block started to slide, even when sliding at different speeds, the distance between the blocks stay more or less a constant. Therefore the kinetic friction would stay a constant. Pulling harder horizontally on the block does not increase the pressure on the table. I.e. it does not increase the normal force between the block and the table. I hope this helps.

[@salatshahid3752]

/: a bit But really thanks a lot (: