Physics, Torque (12 of 13) Static Equilibrium, Ladder Problem

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Static Equilibrium, The Ladder Problem; Shows how to use static equilibrium to determine the force of friction between the bottom of the ladder and the ground surface. The sum of the forces in the x-direction, the sum of the forces in the y-direction and the sum of the torque are set equal to zero.
Torque is a rotating force. It is a measure of how much force is acting on an object that causes the object to rotate. The object will rotate about an axis, which is called the pivot point. It is labeled with the letter P or O. The distance from the pivot point to the point where the force acts is called the moment arm or the lever arm. This distance is labeled with the letter r. This distance r is also a vector, and points from the axis of rotation to the point where the force acts. The force is labeled with the letter F.
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Опубликовано:

11 янв 2015

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Комментарии : 149

@danielsmith6371 3 года назад

i have found in my many college classes that there are 2 types of teachers. teachers like you are the best, they actually want their students to learn and understand. and the other are there to flex their brains so to speak. making thngs way harder than they need to be to appear more impressive.

@stepbystepscience 3 года назад

I appreciate your comment. Thanks very much and best wishes to you.

@anissagonzales3903 6 лет назад

i just watched all 12 of your torque videos and i just want to say thank you so much!!! you help students like me who struggle so much with certain concepts. i feel so much better about my midterm now, thank you for taking the time to make these!

@stepbystepscience 6 лет назад

Great, thanks for commenting and I hope the midterm goes well.

@kelsea7576 6 лет назад

wow my physics teacher makes this so much harder than it needs to be

@xxxFAiRyTaiLxxxD 8 лет назад

best explanation ever. You helped solved my homework

@stepbystepscience 8 лет назад

+Chantel Jose Thanks for the positive comment. You can a listing of all my videos from my website, www.stepbystepscience.com

@wolfrock04 10 месяцев назад

I was just using this to learn ladder examples before my test on momentum and torque and it’s very helpful.

@stepbystepscience 10 месяцев назад

Great to hear! Thanks for watching

@Napkinholdin 3 года назад

My goodness... I'm not so good at this critical thinking sometimes, so given this problem to solve even with all of the tools, I wasn't able to "put it together" like a puzzle. Thank you for the succinct walk-through on how to solve these ladder problems

@stepbystepscience 3 года назад

My pleasure, glad to be helpful!

@jiadavid 4 года назад

I finished all my homework but on the quiz I finished so poorly because I couldn't understand which numbers to plug into the equation. At 5:15 you explained the equation perfectly. I love how you use "r * f * sin()" instead of " f*perpendicular and whatever". Both ways work but I'm glad I've learned about the other way

@stepbystepscience 4 года назад

Great that you found the video explanation to be helpful, thanks for the comment!

@infamousxreaper 8 лет назад

Thank you my good sir. Really helpful for recapping for my AP physics test

@stepbystepscience 8 лет назад

+InfamousReaper Great, hope the test went well. You can see a listing of all my videos at my website, www.stepbystepscience.com

@johnfletcher8129 4 года назад

Thanks so much! I've got my Statics final in about 1.5 hours and this helped a bunch.

@stepbystepscience 4 года назад

Great, hope it goes well!

@christetachausa4179 2 года назад

Thank you for making me understand this concept... It really helped

@stepbystepscience 2 года назад

Glad to hear that, you're very welcome

@aklilumengesha1847 3 года назад

my physics teacher suggested me to watch this really thank u for the brief explanation

@stepbystepscience 3 года назад

You're very welcome! Thanks for watching!

@VOMotion 4 года назад

Yep, this was the video that made me understand after watching multiple lectures and other videos. Thanks!

@stepbystepscience 4 года назад

You are welcome and thanks for letting me know.

@ehansingo8490 11 месяцев назад

Thanks for the detailed explanation 🙏😊

@stepbystepscience 11 месяцев назад

My pleasure 😊, thanks for watching

@paullukak8949 6 лет назад

Amazing lesson. I have a physics final in 8 hours and i learned more from your videos than 3 months of lectures. God Bless!!

@stepbystepscience 6 лет назад

Hope the final went well, thanks for the great comment!

@kem7261 4 года назад

Thank you Sir for the time and patience to teach us!! So clearly explained! Thank you very much

@stepbystepscience 4 года назад

Thank you so much for the great comment.

@DeLaHaProductions 9 лет назад

That helped out a lot thanks! The best explanation of this problem I could find online.

@stepbystepscience 9 лет назад

@Ben Fox, thanks for the "best" comment, I think they turned out pretty well but they (static equilibrium videos) have not gotten much traffic yet. Tell all your friends.

@DeLaHaProductions 9 лет назад

Will do! I'll be checking out some more later as well.

@divyanshagg1125 3 года назад

thanks!! i needed it soo much for my pre-medical entrance exam

@stepbystepscience 3 года назад

You're welcome and best of luck!

@Joey-nh4wy 2 года назад

God bless you Sir!!! Thanks alot for your vidoes

@stepbystepscience 2 года назад

So nice of you, you are most welcome.

@JesusMartinez-zu3xl 3 года назад

you made this problem so easy to follow!

@stepbystepscience 3 года назад

Thanks, it is a complicated one.

@aashbipin4993 2 года назад

Thank u for ur clear cut explanation sir...☺️

@stepbystepscience 2 года назад

Most welcome, thanks for watching!

@XxbrownbxX 8 лет назад

Thank You Very Much! This was clear, and just what I needed

@merrymekoro2206 2 года назад

Thank you Sir!!! It's very helpfull

@stepbystepscience 2 года назад

Most welcome!

@BarcaOwl 5 лет назад

Thanks man, feels bad when you say that's alot to do and my physics department is probably laughing at the prospect of putting a problem so simple to them on the exam.

@stepbystepscience 5 лет назад

No problem, thanks for watching.

@ptyptypty3 5 лет назад

Most Excellent!! thank you... great graphics... that's a cool program you're using.... so easy to read and follow...

@stepbystepscience 5 лет назад

Thanks for the positive comment. It is not really a program, just Apple Keynote with animations. Works pretty well.

@timychanga 5 лет назад

Thank you! Your explanations were really helpful

@stepbystepscience 5 лет назад

Anytime, thanks for the comment.

@albertpicher3910 7 лет назад

Really clear explanation. thanks a lot!

@thammyxolani9736 6 лет назад

Thank you Sir you my best lecture ever may God bless

@stepbystepscience 6 лет назад

Very nice of you to say....thanks for watching and commenting.

@peterholmes1736 Год назад

I'll start off by saying thank you so much for these videos! I'm studying physics with the OU alongside my full-time job and having content like this really helps me understand concepts faster than using my textbooks! A quick question on this though, would there not be a coefficient of friction where the ladder meets the wall? Assuming the ladder is stationary there would be a coefficient of static friction and if the ladder were sliding there would be a coefficient of sliding friction.

@stepbystepscience Год назад

We assume there is no friction between the wall and the ladder.

@diamondaka4559 7 лет назад

That was really awesome...... Keep it....!much appreciate

@birukchiche7233 3 месяца назад

Outstanding 🎉

@stepbystepscience 3 месяца назад

Thanks so much!

@cfopeter102 6 лет назад

Great explanation of the problem, thank you sir!

@stepbystepscience 6 лет назад

you are very welcome.

@muhammedsillah3363 2 года назад

May the lord reward your hardwork

@stepbystepscience 2 года назад

Thank you so much. Best wishes to you!

@vijgenboom2843 2 года назад

Excellent! Thank you ❤️.

@stepbystepscience 2 года назад

You are welcome!

@AbrhaArsema 4 месяца назад

I have great thanks for you .keep it up 💯💯💯💯💯 percent

@stepbystepscience 4 месяца назад

Thank you too!

@Zackarysmackary 7 лет назад

Great video, dude!

@matthewbarna2241 3 года назад

Great video!

@stepbystepscience 3 года назад

Thanks, glad you liked it!

@andrewcarnegie7860 5 лет назад

Just a query can we take torque from the point on the wall? Btw nice lecture

@AdamBehnam 5 лет назад

Thanks bro! With this video I subscribed to your channel! :)

@stepbystepscience 5 лет назад

Thanks for subscribing

@lessejesse10 5 лет назад

How do you decide which point is best to take the torque from?

@stepbystepscience 5 лет назад

The pivot point.

@jimpy2731 2 года назад

So in theory, if we solve for the friction force like we do in the video, but also find the magnitude of the normal force in by summing the forces in the y direction, we could find the value of mu correct?

@lokkilokesh4388 8 лет назад

clearly understood sir thanq this makes me good marks in my semister

@stepbystepscience 8 лет назад

Hope the semester ends well. You can see a listing of all my videos at my website, www.stepbystepscience.com

@srijanbhowmick9570 3 года назад

Why are we choosing the bottom end of the ladder to calculate the torque ? Why can't we use the center of mass of the ladder ?

@Shackled 4 года назад

So good!

@stepbystepscience 4 года назад

Nice, thanks!

@ptatoe16 5 месяцев назад

You said that the x distances given are the lever arms, but this doesn’t really make sense to me. With our torque equation where Tp + Tl = Tw, are we not talking about torques acted upon the ladder? Therefore, the ladder should be our lever arm right? However if we treat the x distances as lever arms, this ends up being the torques that the forces produce onto the floor, which doesn’t make sense

@stepbystepscience 5 месяцев назад

Good question, but starting at about 5:00 minutes into the video I explain how we get around the fact that we do not know the lever arm.

@shaurya4335 Месяц назад

I found out how he got it. I would recommend some paper to visualise the setup. Take the force F_n 1.1 meters from our pivot point. Let L be the length of the ladder from the pivot point. The torque there is given by sin(theta)F_n*L. So, lets find L! Now with the paper draw a dotted line from the F_n to the ground. (paper coming in clutch now) Notice how this forms a triangle, where the angle theta is the same as the theta in sin(theta)F_n*L. In this new triangle, 1.1m is the Opposite, while L is the Hypotenuse (zamn I spelt it correct). Since Sin(theta)= Opp/Hyp, it is the same as Sin(theta)= 1.1/L. Heyyy, wait a minute, we now have to expressions with sin(theta). Lets plug in our new expression for Sin(theta) = 1.1/L into our torque equation Torque = sin(theta)F_n*L. That would mean Torque = sin(theta)F_n*L -(note: subbing in sin(theta) as 1.1/L ) Torque = (1.1/L) F_n*L. -(note: L denominator and L cancel) Torque = 1.1*F_n And there you have it! Thats just the perpendicular side times at the Force! Let me know if u didn't understand anything, or want me to draw something up. ps. F_n is F subscript n, hope that didn't confuse you.

@harishchauhan6613 Год назад

Thank you sir

@stepbystepscience Год назад

My pleasure, thanks for watching

@billvibetti6003 3 года назад

5.5m is the vertical distance from the pivot, aren't we supposed to use horizontal (perpendicular) distances ??

@jessicalaczny2936 5 лет назад

Why aren't the weight forces broken down into components? Aren't they both at angles instead of being perpendicular to the ladder?

@stepbystepscience 5 лет назад

because they are acting in the y direction, not between the x and y directions.

@HashBandicoot356 7 лет назад

TY very well explained.

@stepbystepscience 7 лет назад

Thanks. You can also see a listing of all my videos by topic at www.stepbystepscience.com

@calypzo9361 5 лет назад

You're the man!!!

@stepbystepscience 5 лет назад

Ok, and thanks for the comment.

@aayushkhanduri594 4 года назад

nice explaination

@stepbystepscience 4 года назад

Thanks and you are very welcome.

@richtervaneeden3287 7 лет назад

do one on momentum

@thomasj.jr.1019 6 лет назад

I love this but I still dont get that Xl and Xp, did u get those Xl and Xp from the question or did u just count them ? Thank you 😭

@sarthakshrivastava4480 4 года назад

This is about 2 years too late, but those are given in the question

@tilakpatel2106 5 лет назад

Shouldn't the Ff be (-247N)? It's in the opposite direction.

@vanessaantuna9663 7 лет назад

I appreciate this so much thanks!

@stepbystepscience 7 лет назад

You are very welcome. You can see a listing of all my videos at www.stepbystepscience.com

@valerie.mccaffrey 5 лет назад

helpful, thank you!

@stepbystepscience 5 лет назад

You are very welcome.

@amylucas6384 6 лет назад

Super helpful

@chasefarrell3755 3 года назад

This dude talks faster than anyone I've ever heard but still is easier to understand than my professor.

@stepbystepscience 3 года назад

Glad it was clear and understandable!

@sethother8012 2 года назад

At 3:39 when you said, “if these forces were to act by themselves, the would cause the ladder to rotate in the counter-clockwise direction” did you mean clockwise?

@sethother8012 2 года назад

Those downward forces are clockwise, aren’t they?

@sethother8012 2 года назад

Well, i guess that just depends which normal force you get rid of to allow rotation. its only counterclockwise if you get rid of the wall. If yiu getvrid if the ground, it goes clockwise

@sethother8012 2 года назад

Its because axis of rotation is at base of ladder

@138suhasvardhan4 4 года назад

Thank u sir

@alwysrite 8 лет назад

Are we assuming that friction between ladder and wall = zero for this example?

@stepbystepscience 8 лет назад

Yes, You can see a listing of all my videos at my website, www.stepbystepscience.com

@llawliet405 5 лет назад

thnk you

@stepbystepscience 5 лет назад

You are very welcome, thanks for commenting!

@lclow5053 7 лет назад

BEST

@foongyeeng6332 7 лет назад

How is the lever arm of the force from the wall (Fw) 5.5m when the pivot point is set at the base of the ladder touching the ground?

@foongyeeng6332 6 лет назад

Hey, actually I think I might have figured it out. When using the formula 'torque= r x F', we substitute the values 'torque= 5.5m x Fw' but if we choose to use the formula 'torque= r x F x sin θ', we substitute the values r= length of ladder, F=Fw , sin θ= sine of angle between the horizontal Fw and ladder or alternatively, sin θ= opposite/hypotenuse= 5.5m/length of ladder, all these into 'torque= r xF x sin θ' and the torques would be the same. Hope this helps!

@shaurya4335 Месяц назад

Alas 6 years later I have the same question, that I just solved using your comment. Thanks. I just wish he had explained it as thoroughly as he usually does.