Hey man, I just want to let you know that I am in a top 40 US university and your youtube physics videos are currently being used as required watching for our online Physics class. Great job, you explain everything very clearly and it helps a ton. Watching this right now in preparation for a quiz!
Thanks for all of these great videos ever made . I can't understand one thing the force of the friction is independent but even when there is no force applied there is always a force causing the friction direction to happen
This is your second lesson I watched today; your explanation is very well. However, in this particular video, I miss a demonstration about how top static friction is always higher than the relative cinematic friction.
Are the shirts on the bed put together to form a seahawk's head ?? My school's mascot looks just like that. The seahawk has a black and yellow head and a black and red beak. Maybe I just spent too much time looking for Carmen Santiago as a kid !! LOL Thank You for these wonderful free videos. I have donated in the past and will continue to do so. Please viewers, donate if you can, even just a few dollars a year. These videos take a LOT OF TIME. LOL It's a full time job !! And Professor Jonathan is one of the best !!! Happy New Year to All !!
Thanx...It was great Could u add a video bout determining the direction of the static force of friction ... i guess it too opposes the relative motion !
i have a question. when a body is just placed on a horizontal surface and the static friction force is acting on it why does the boy not move backward? I am kind of lost at this point
The force of static friction can change. It has a maximum value, which is the coefficient of static friction times the normal Force. The force of static friction is always less than or equal to the maximum value. The force of static friction can increase and decrease in order to stop the object from moving.
@@jojopyun Thanks very much. I understood that already I actually figured out that when there is no force acting on the body the static friction also is not present but when a force acta it tries to oppose until it reaches its max value. I actually understood just that I thought for some minutes that the friction will act when no force is making the body move😂😂which is just crazy. Thanks
This website has a good description: www.dummies.com/education/science/physics/how-surface-area-affects-the-force-of-friction/ "The force due to friction is generally independent of the contact area between the two surfaces. This means that even if you have two heavy objects of the same mass, where one is half as long and twice as high as the other one, they still experience the same frictional force when you drag them over the ground. This makes sense, because if the area of contact doubles, you may think that you should get twice as much friction. But when you double the length of an object, you halve the force on each square centimeter, because less weight is above it to push down. Note that this relationship breaks down when the surface area gets too small, since then the coefficient of friction increases because the object may begin to dig into the surface." Hope that helps.
Could we adopt a more general definition of "applied force" and let gravity qualify as an applied force? Would it be accurate, then, to say that static friction opposes the net applied force when the object is in equilibrium?
+jdmphys 1) I don't see how the Force of Gravity would ever qualify as a Force Applied. The Force of Gravity is a Field Force, the Force Applied is a Contact Force. Very different. 2) The "net applied force" would only be the addition of multiple applied forces.
+Flipping Physics Yes, fair point--makes sense. Let's just call it 'the net external force parallel to the surface due to everything except friction, as measured in the object's frame.' Does static friction always oppose this? I guess I'm trying to figure out what the one general rule is for determining the direction of static friction.
+jdmphys And in particular, I'm trying to synthesize this scenario with (a) a ball that is rolling without slipping, and (b) a car moving around an unbanked circular track.
+jdmphys Imagine the direction the objects would move (or rotate) in the absence of friction. The force of friction is opposite that direction. For (a) a ball rolling down an incline without friction, the ball won't actually "roll" because it is friction that causes the ball to rotate. If it is rolling without slipping, then the force of static friction would be up the incline. For (b) in the absence of friction, the inertia of the car would make it move in a straight line. Relative to the in/out direction one should sum the forces in when analyzing circular motion, this would be out, away from the center of the circle the motion of the car describes. Therefore the force of friction will be opposite that or in toward the center of the circle. Does that help?
+Flipping Physics Yes, this helps a ton! Thanks! With the circular motion example, is it correct that the velocity is tangent to the circle? Assuming so, this makes me think that the rule would have friction pointing tangent rather than into the circle, because if friction suddenly disappeared, then the car would move off along a straight line tangent to the circle. How is the rule able to be sensitive to our in/out convention for summing forces when in circular motion? Is there something we can articulate further about the rule which captures this "sensitivity" (as I'm calling it) to our force convention in the case of circular motion? If we stepped into the car's non-inertial frame, there would be a centrifugal force pointing out away from the center of the circle, ye? In this case, it would be correct to use a rule that static friction opposes the net external force from all other forces parallel to the surface in the car's frame, I think...
In the last case There is a component of mg working toward down the incline. 🙁 And friction working opposite with that component. So is it Independent of Force applied on it? Or I got that wrong?
The point is that there is no general rule which compares the direction of the force of friction to the direction of the force applied. I can (and have) shown examples where the force of friction is in the same direction as the force applied and all sorts of other angles relative to the force applied. In summation, do not use the force applied as a reference for the direction of the force of friction!
When there is no applied force (or zero net force) on an object, the frictional force is also zero. If it wasn't, it would cause a non-zero net force on the object and it would accelerate, per Newton's 2nd Law.
Anik Talukder Generally we consider anything on ice "frictionless", however, it is not quite frictionless; it would have a very small coefficient of friction. Perhaps I should make a video measuring the coefficient of friction of ice on ice? That sounds like fun!
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Hey man, I just want to let you know that I am in a top 40 US university and your youtube physics videos are currently being used as required watching for our online Physics class. Great job, you explain everything very clearly and it helps a ton. Watching this right now in preparation for a quiz!
That is awesome! I am so glad to help college students as well!
Have your teacher or school fund Mr. P on Patreon :)
I appreciate the work man, it's amazing. Wish you were my teacher
+soheil rasekhi You are welcome. Glad to be helping you out!
I watched this for my Conceptual Physics class today, it gave me a better understanding Thank you so much!
Probably the only easy explanation I could find on RUclips.
Awesome way of demonstration.....
✨😇✨
Thank you so much...
It feels really lucky that I know this channel.....
Thank you for your kind words
Thanks for all of these great videos ever made . I can't understand one thing the force of the friction is independent but even when there is no force applied there is always a force causing the friction direction to happen
Dope editing man! keep it up like this!!
I will do my best to keep it going. Thanks!
Thank you sir...I was stuck with this problems for two days but now it's quite simple with the assistance of your skillful explanations...
You are most welcome
This is your second lesson I watched today; your explanation is very well. However, in this particular video, I miss a demonstration about how top static friction is always higher than the relative cinematic friction.
This makes it so much easier to understand. Thank you!
Mind Blowing editing! With mind blowing teaching!
Thank you so much 😀
I may have stepped off the deep end a bit; hopefully you will join me. Here is a video project created by Bobby. #PhysicsED #APPhysics1
needs more views. loved the explanation.
Thank you, great video, well explained!
0:06
Yay, now I know at least one voice in the Flipping Physics harmonization
Is it SAT or SATB?
The Campaign For Clear English here in London, England would approve of this video.
I'll take that compliment.
Outstanding explanation sir ...🤗
Thank you👍🏻 great presentation ❤
Are the shirts on the bed put together to form a seahawk's head ?? My school's mascot looks just like that. The seahawk has a black and yellow head and a black and red beak. Maybe I just spent too much time looking for Carmen Santiago as a kid !! LOL Thank You for these wonderful free videos. I have donated in the past and will continue to do so. Please viewers, donate if you can, even just a few dollars a year. These videos take a LOT OF TIME. LOL It's a full time job !! And Professor Jonathan is one of the best !!! Happy New Year to All !!
The textbook I read unfortunately doesn’t focus on the definitions so it cases a confusion. Thanks a lot
Unique teacher for me...physics is fun Mann
I totally agree; physics is fun. I'll pass the word on to Bobby.
Thanks so much for taking my word...!!!
Thank you Bobby:)
Amazing video. Among editing. Very well taught
Thank you!
Thanx...It was great
Could u add a video bout determining the direction of the static force of friction ... i guess it too opposes the relative motion !
+Atul Saswat I go over the direction of the force of friction in this video: www.flippingphysics.com/friction-equation.html
+Flipping Physics thnx !
😮 This is amazing! Now I think I'm ready for our test. Hopefully I won't mess up. 😭
Thanks. I'll pass the word on to Billy. Good luck on your test!
Thank you for making me love physics
You're very welcome!
so mass affects friction but will the angle of the surface be the same when measuring both kinetic and static?
Ooo bobby your are amazing!!
I'll let him know!
Thank you for the great effort.
You are welcome!
you did good job man.
Thanks. Hope you learned something.
Wow, it's amazing, Bobby, I enjoy leaning with you.😀
+Sokunthea Ngoun Thanks. I'll pass the word along to Bobby.
these videos are really helpful! thank you!
You are welcome. I'll pass the word on to Bobby that you feel his video was helpful.
Flipping Physics haha! sure!
i have a question. when a body is just placed on a horizontal surface and the static friction force is acting on it why does the boy not move backward? I am kind of lost at this point
The force of static friction can change. It has a maximum value, which is the coefficient of static friction times the normal Force. The force of static friction is always less than or equal to the maximum value. The force of static friction can increase and decrease in order to stop the object from moving.
@@jojopyun Thanks very much. I understood that already I actually figured out that when there is no force acting on the body the static friction also is not present but when a force acta it tries to oppose until it reaches its max value. I actually understood just that I thought for some minutes that the friction will act when no force is making the body move😂😂which is just crazy. Thanks
you still active bro?
Salam You say that friction force does not depend upon surface how it is correct?Explain further!!!
This website has a good description: www.dummies.com/education/science/physics/how-surface-area-affects-the-force-of-friction/
"The force due to friction is generally independent of the contact area between the two surfaces. This means that even if you have two heavy objects of the same mass, where one is half as long and twice as high as the other one, they still experience the same frictional force when you drag them over the ground. This makes sense, because if the area of contact doubles, you may think that you should get twice as much friction. But when you double the length of an object, you halve the force on each square centimeter, because less weight is above it to push down. Note that this relationship breaks down when the surface area gets too small, since then the coefficient of friction increases because the object may begin to dig into the surface."
Hope that helps.
Could we adopt a more general definition of "applied force" and let gravity qualify as an applied force? Would it be accurate, then, to say that static friction opposes the net applied force when the object is in equilibrium?
+jdmphys 1) I don't see how the Force of Gravity would ever qualify as a Force Applied. The Force of Gravity is a Field Force, the Force Applied is a Contact Force. Very different.
2) The "net applied force" would only be the addition of multiple applied forces.
+Flipping Physics Yes, fair point--makes sense. Let's just call it 'the net external force parallel to the surface due to everything except friction, as measured in the object's frame.' Does static friction always oppose this? I guess I'm trying to figure out what the one general rule is for determining the direction of static friction.
+jdmphys And in particular, I'm trying to synthesize this scenario with (a) a ball that is rolling without slipping, and (b) a car moving around an unbanked circular track.
+jdmphys Imagine the direction the objects would move (or rotate) in the absence of friction. The force of friction is opposite that direction. For (a) a ball rolling down an incline without friction, the ball won't actually "roll" because it is friction that causes the ball to rotate. If it is rolling without slipping, then the force of static friction would be up the incline. For (b) in the absence of friction, the inertia of the car would make it move in a straight line. Relative to the in/out direction one should sum the forces in when analyzing circular motion, this would be out, away from the center of the circle the motion of the car describes. Therefore the force of friction will be opposite that or in toward the center of the circle. Does that help?
+Flipping Physics Yes, this helps a ton! Thanks! With the circular motion example, is it correct that the velocity is tangent to the circle? Assuming so, this makes me think that the rule would have friction pointing tangent rather than into the circle, because if friction suddenly disappeared, then the car would move off along a straight line tangent to the circle. How is the rule able to be sensitive to our in/out convention for summing forces when in circular motion? Is there something we can articulate further about the rule which captures this "sensitivity" (as I'm calling it) to our force convention in the case of circular motion?
If we stepped into the car's non-inertial frame, there would be a centrifugal force pointing out away from the center of the circle, ye? In this case, it would be correct to use a rule that static friction opposes the net external force from all other forces parallel to the surface in the car's frame, I think...
Thank you, this helped me SO much.👏🏻👌🏻
Thanks. I'll let Billy know.
li
thanx man....u helped me again!😄
You are welcome. Always glad to help!
In the last case There is a component of mg working toward down the incline. 🙁 And friction working opposite with that component. So is it Independent of Force applied on it? Or I got that wrong?
The point is that there is no general rule which compares the direction of the force of friction to the direction of the force applied. I can (and have) shown examples where the force of friction is in the same direction as the force applied and all sorts of other angles relative to the force applied. In summation, do not use the force applied as a reference for the direction of the force of friction!
@@FlippingPhysics Ok sir. Thank you! ❤️
when body is at rest and no pushing applied force is there...what is the magnitude of frictional force?
When there is no applied force (or zero net force) on an object, the frictional force is also zero. If it wasn't, it would cause a non-zero net force on the object and it would accelerate, per Newton's 2nd Law.
I LOVE YOUR VIDEOS:) :) :)
Thanks a lot that makes sense.
You are welcome. Glad to help.
Love this video...👍
Great! I'll pass the word on to Bobby. I am sure he would love to know.
nice explain
Say i have an ice cube, and a floor with ice as its surface will there be no friction or some friction because it seems smooth
Anik Talukder Generally we consider anything on ice "frictionless", however, it is not quite frictionless; it would have a very small coefficient of friction. Perhaps I should make a video measuring the coefficient of friction of ice on ice? That sounds like fun!
Yeah that would be great!
Thank you very much :)
You're welcome!
Sir u are amazing
What is ur actual name
Hi Bobby! I love your video! Do your socks match?
Glad you enjoy Bobby's video. I'll pass the word on to him.
I can tell you his socks rarely match.
When moving the ice cube
Amen thanks for enlightening me jesus :)
You are welcome for the enlightenment. I'll pass the good word on to Bobby.
I love you.
+Ayesha Shehzad Love you too!
Can you please come and be my teacher
I am your teacher. Did you not just learn from me?
lovely
thanks.
my right ear enjoyed this
ha ha ha
the guy made me laugh
+Deena Dayalan Sweet! I'll pass the word on to Bobby.
niceeee!!! :D.
thanks.
🇵🇬🇵🇬,,,
r u twins
flippingphysics.com/making-a-video.html
Put on some normal clothes pls
Why?
when body is at rest and no pushing applied force is there...what is the magnitude of frictional force?
The answer depends on the situation. I would suggest: www.flippingphysics.com/free-body-diagrams.html