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Mechanical Engineering: Particle Equilibrium (11 of 19) Why are Pulleys a Mechanical Advantage? 

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In this video I will calculate and explain the mechanical advantage of using pulleys.

Next video in the Particle Equilibrium series can be seen at:
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23. juni. 2015

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Kommentarer 919   
Michael Duvall
Michael Duvall Dag siden
Golly gee mr. Wizard. You made the complicated easy to understand......
Michel van Biezen
Thanks!
TheRadioAteMyTV
TheRadioAteMyTV 2 dager siden
I almost thumbed down due to the bow tie, but the brilliant and plain teaching swayed me not to.
Walker Moses
Walker Moses 10 dager siden
thank you
Michel van Biezen
Michel van Biezen 8 dager siden
You're welcome
Norensen Simanjuntak
Norensen Simanjuntak 11 dager siden
Anime, Dr. Stone in aplication 😁
Wikum Silva
Wikum Silva 12 dager siden
Thank u very much sir 🙏
Michel van Biezen
Michel van Biezen 12 dager siden
Most welcome
Agan Sanysi
Agan Sanysi 13 dager siden
so, 100/1, 100/2, 100/3, & 100/4 depends on the number of string. Better explanation than my univ prof haha
K.R Technosafe Engineers
only for sheev of pulley is used out of five on mobile crane then how much capacity will be reduced for mobile crane?
MatterLabz
MatterLabz 16 dager siden
Excellent explanation! Thank you for your efforts!
Michel van Biezen
Michel van Biezen 16 dager siden
Glad it was helpful!
arpit kumar
arpit kumar 17 dager siden
Dr. Stone brought me here. If only I had watched this in high school. Now I am working as a software engineer and I don't need to use this information about pulleys but watching the Dr. Stone anime made me interested in science again and a lot more. I highly recommend that anime if you are interested in science
Water Tiger
Water Tiger 18 dager siden
thanks
Michel van Biezen
Michel van Biezen 18 dager siden
You're welcome!
Teyanvrinn
Teyanvrinn 24 dager siden
I know it’s probably the norm, but I am so happy to see the metric system in an US physics video
Michel van Biezen
Michel van Biezen 23 dager siden
You're welcome 😊
Michaks91
Michaks91 Måned siden
I was wondering for so long how the hell does this work Thank you :D
Michel van Biezen
Michel van Biezen Måned siden
Glad it helped!
venkateshs1959
venkateshs1959 Måned siden
Sir, where to choose the boundary for the FBD is tricky. If I choose it wrongly, i get wrong result. Especially in the arrangement 4. Request your help
venkateshs1959
venkateshs1959 Måned siden
@Michel van Biezen Thank you very much, Sir
Michel van Biezen
Michel van Biezen Måned siden
The boundary of the FBD is chosen so that you can determine the forces acting on what is inside the FBD. Essentially you cannot pick "wrong", but your choice of where to place the boundary must match which forces you are trying to determine.
venkateshs1959
venkateshs1959 Måned siden
Great Lectures by the prof. thank you very much. One question - in second arrangement, why should the distance moved be twice compared to the first one?
venkateshs1959
venkateshs1959 Måned siden
@Michel van Biezen Thank you very much, Sir
Michel van Biezen
Michel van Biezen Måned siden
The change in length (distance traveled) on the rope being pulled must equal the distance traveled on both side of the pulley being pulled up, so you get a 2:1 ratio compared to the distance traveled by the weight
Marching Fellow
Marching Fellow Måned siden
Professor : At 4:27 you begin discussing the last combination and I wonder if it may have been helpful to spend a little time explaining why the free body diagram you drew included the bottom two pulleys - ie the general rule is that it must have a boundary through the maximum number of suspending ropes / lines ?
Michel van Biezen
Michel van Biezen Måned siden
There is no hard and fast rule as to where you place the boundaries of the free body diagram. You place it in a particular place in order to gain some information about the system, by isolating some specific force or forces.
Caelee Schoeman
Caelee Schoeman Måned siden
sir you just cured my depression
KRISH RAJ [X A] 32
KRISH RAJ [X A] 32 Måned siden
Sir diagrams are fantastic
Michel van Biezen
Michel van Biezen Måned siden
Thank you!
Yacine Cabba
Yacine Cabba Måned siden
you deserve a Nobel prize
Michel van Biezen
Michel van Biezen Måned siden
Thank you!
HSC Study
HSC Study Måned siden
Excellent explanation ❤️ Love from Bangladesh
Michel van Biezen
Michel van Biezen Måned siden
Thank you and welcome to the channel!
telomere centromere
telomere centromere Måned siden
Thank you that made sense
Michel van Biezen
Michel van Biezen Måned siden
You're welcome!
MEGA SUPER NOVA
MEGA SUPER NOVA Måned siden
simplest formula force applied=weight of load/no. of pully
MEGA SUPER NOVA
MEGA SUPER NOVA Måned siden
@Michel van Biezen also amazing video keep it up
MEGA SUPER NOVA
MEGA SUPER NOVA Måned siden
@Michel van Biezen yes, it's just a trick only for this situation, otherwise machinal advantage =force out/force in R(resultant force) =f-mg where f can be tension
Michel van Biezen
Michel van Biezen Måned siden
That does not always work. There are pulley arrangements that do not fit that equation.
commonerIndian
commonerIndian Måned siden
nice
Michel van Biezen
Michel van Biezen Måned siden
Thanks
Jagannath Gavhale
Jagannath Gavhale 2 måneder siden
Did is there a role of pulley size. Will it make change to move weight up.
Michel van Biezen
Michel van Biezen 2 måneder siden
The pulley size doesn't matter so long the relative size of the pulleys allow the ropes to be vertical.
AJ
AJ 2 måneder siden
Awesome lecture! I wish I found these lectures years ago when I took introductory mechanics so I would've loved and appreciated it more.
Michel van Biezen
Michel van Biezen 2 måneder siden
Glad it was helpful!
Ashish Giri
Ashish Giri 2 måneder siden
Observation here in 4th case if we start drawing the string in opposite direction then the mechanical advantage is 5 but velocity ratio is 4 :l
Ashish Giri
Ashish Giri 2 måneder siden
@Michel van Biezen ya its actually an error this makes its efficiency 125 % which is not possible
Michel van Biezen
Michel van Biezen 2 måneder siden
The mechanical advantage and the velocity ration must be the same.
Clayton Hawk
Clayton Hawk 2 måneder siden
Thank you You're great at explaining this
Michel van Biezen
Michel van Biezen 2 måneder siden
You're very welcome!
loneinvestor
loneinvestor 3 måneder siden
Yeah but HOW is just adding longer rope around increasing wheels making a lighter load??? Plenty of people explain what works but never HOW.
Michel van Biezen
Michel van Biezen 3 måneder siden
That is explained in the video. The free body diagram shows that on the first diagram the load is supported by 1 cable. On the second diagram the load is distributed over 2 cables On the second diagram it is shown how the load is divided over 3 cables And on the 4th diagram the load is supported by 4 cables.
Cynthia Bentley
Cynthia Bentley 3 måneder siden
Excellent demonstration. !!
Michel van Biezen
Michel van Biezen 3 måneder siden
Glad you liked it!
cozy powell
cozy powell 3 måneder siden
Thanks
Michel van Biezen
Michel van Biezen 3 måneder siden
Welcome
Maria Dubyaga
Maria Dubyaga 3 måneder siden
Amazing. Such a great explanation, as usual :) thank you!
Michel van Biezen
Michel van Biezen 3 måneder siden
Our pleasure!
a binocular
a binocular 3 måneder siden
Thank you
Michel van Biezen
Michel van Biezen 3 måneder siden
You're welcome
medusa grega
medusa grega 3 måneder siden
Ótima explicação!
gathme
gathme 3 måneder siden
.. absolutely fantastic.. 👍
Michel van Biezen
Michel van Biezen 3 måneder siden
Glad you enjoyed it
WikTheCloudKid
WikTheCloudKid 3 måneder siden
That helped me understand it so well thank you
Michel van Biezen
Michel van Biezen 3 måneder siden
Glad it helped!
Shah Alam
Shah Alam 3 måneder siden
The most difficult part is to draw the free body diagram.... based on what did you choose the dotted rectangle? lol
Michel van Biezen
Michel van Biezen 3 måneder siden
The boundary of the free body diagram is placed at the location where you want to consider the forces being exerted to the portion of the system inside the box. Try to draw the boxed at different locations and see what happens. In this case the boundary of the free body diagrams cut across the cable for which you want to know the force. (Remember that the laws of Newton apply)
Conor Alvezi
Conor Alvezi 3 måneder siden
pulleys are also none of the poop
St. Devil
St. Devil 3 måneder siden
In the 4th diagram, what is the reason for drawing free body diagram across 2 pulleys, why not across only the main pulley which is directly holding the weight or why not across the lower 3 pulleys? He did not explain that.
St. Devil
St. Devil 3 måneder siden
@Michel van Biezen Thanks a lot for explaining it.
Michel van Biezen
Michel van Biezen 3 måneder siden
You can place a free body diagram around any one or any number of pulleys. The location of the free body diagram was chosen to cut through the maximum number of ropes since all of them play a role in holding up what is below the "cut" line.
marcochimio
marcochimio 4 måneder siden
Great explanation, BUT how do you know how many objects to include in your free body diagram?
Michel van Biezen
Michel van Biezen 4 måneder siden
In the first diagram there is only 1 cable that hold up the weight, so I placed a FBD around the weight. On the second diagram, there are two cables from which the weight is suspended, so I placed a FBD around the weight and the bottom pulley so the border cuts through both cables. On the third diagram there are 3 cables holding up the weight, so the FBD diagram is placed so that the border cut through all 3 cables. You could also have drawn the FBD to include the bottom 2 pulleys which would have the border of the FBD cut through those 2 cables, and you could have used that the determine the tension in those 2 cables. There is no rule. You can place the FBD anywhere to give you the desired information.
marcochimio
marcochimio 4 måneder siden
@Michel van Biezen I see all of that, but how did you know to select the FBD around only the mass in #1, the mass and one pulley in #2 & #3, and the mass and 2 pulleys in #4? What informs you where you cut the FBD off? Is there a rule that I should follow?
Michel van Biezen
Michel van Biezen 4 måneder siden
The boundary of the free body diagram, cuts through the cables and indicates the forces acting on whatever is inside the box. That is how you determine where you want to place the free body diagram. Wherever you want to consider the forces is where you place the boundaries.
Avangard
Avangard 4 måneder siden
this helped me soooo much, thank you kind man!
Michel van Biezen
Michel van Biezen 4 måneder siden
Glad it helped!
Brang Ja
Brang Ja 4 måneder siden
You can actually pull a car single handedly using this method. Trust me, I've done that.
Andrew Couto
Andrew Couto 4 måneder siden
The bow tie reminds me of peewee Herman. Good lecture though❤️
Luke the grifter
Luke the grifter 4 måneder siden
So simple! Thank you Sir! No formulas, just common sense.
Michel van Biezen
Michel van Biezen 4 måneder siden
Glad it helped!
Robert Kattner
Robert Kattner 4 måneder siden
Why not say one kilogram instead of newtons? More people would understand.
Nicke H
Nicke H 4 måneder siden
Meter!👍
bestamerica
bestamerica 4 måneder siden
' not really... some no and some yes... depend on the pulley wheel size
bestamerica
bestamerica 4 måneder siden
@Need2connect hi N... ' thank explain... a pair of ball bearings with the pulley wheel would be little easily pull... without ball bearing is a little hard pull
Need2connect
Need2connect 4 måneder siden
did you not hear where he said many times over that we are assuming the pulley has no mass and no friction. So this is exactly correct. Although in the real world the pulley would have mass and friction. He explained that all.
titaniumsandwedge
titaniumsandwedge 4 måneder siden
What you see in this video is BS. Van Biezen is pulling your leg.
MrKibitz
MrKibitz 4 måneder siden
Stupid shit, this world is doomed!!! It’s all about the proportion: length of 180 degree arc on pulley disc TO its radius)
Four Toes
Four Toes 4 måneder siden
Oh dear - bow tie says it all!
Joecake Gamedev
Joecake Gamedev 4 måneder siden
You are a spectacular teacher! :D
Michel van Biezen
Michel van Biezen 4 måneder siden
Thank you! 😃
jack li
jack li 4 måneder siden
wait wait wait, does that mean if i have enough pully i can pull the earth with my middle finger?
Michel van Biezen
Michel van Biezen 4 måneder siden
If you can find a place to anchor the pulleys, yes.
broccoli
broccoli 4 måneder siden
I have watched SIX explanations of pulleys and I still have no idea how they work. I can follow the math. I know how to use pulleys. I can see that I am applying smaller forces over larger distances to move the object. But I couldn't for the life of my explain why it works. You might as well be describing the flow of black magic through the aether.
Mr Hyde
Mr Hyde 4 måneder siden
Can you show cremona? I forgot.
14 y 十1
14 y 十1 4 måneder siden
Now I am ready to be an engineer!!
Alberto Pellegrino
Alberto Pellegrino 5 måneder siden
So for a infinite number of pulley in series like these, the force to apply for lift our little blocks is 0?
Alberto Pellegrino
Alberto Pellegrino 4 måneder siden
@Michel van Biezen indeed, thx 😊
Michel van Biezen
Michel van Biezen 5 måneder siden
As the limit approaches infinity, the force required will approach zero. It can never be infinity and zero (in the real world)
Saved By Jesus
Saved By Jesus 5 måneder siden
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Chocolate kun
Chocolate kun 5 måneder siden
why am I supposed to study this in grade 7 My school is insane
TheRadioAteMyTV
TheRadioAteMyTV 2 dager siden
I am having 2nd graders learn it, so what does that make them?
Fernando López
Fernando López 5 måneder siden
Thank you!
Michel van Biezen
Michel van Biezen 5 måneder siden
You're welcome!
aubin tasse
aubin tasse 5 måneder siden
Yeah but will this work in real life? I just can't visualise it specially because of the line in the middle of each pulley. How will the hole system move when the rope gets pulled?
Michel van Biezen
Michel van Biezen 5 måneder siden
That is a great idea.
aubin tasse
aubin tasse 5 måneder siden
@Michel van Biezen I know it is much to ask but is it possible to see some practicals? Can you please demonstrate all those different systems?
Michel van Biezen
Michel van Biezen 5 måneder siden
It works great in real life.
gmail Google
gmail Google 5 måneder siden
Thank you Very good From iran
Michel van Biezen
Michel van Biezen 5 måneder siden
Welcome to the channel!
Shimaal Carrim
Shimaal Carrim 5 måneder siden
Best teacher ever
Al'set Barnabi
Al'set Barnabi 5 måneder siden
unfortunately he doesn't explain how to establish the free body diagram - doesn't show at which point along the system and why!
Need2connect
Need2connect 4 måneder siden
This is one video of a 19 part series
thomas
thomas 5 måneder siden
Great explanation as to why. Could we conclude the force much faster by saying F= w / number of pulleys?
Michel van Biezen
Michel van Biezen 5 måneder siden
Not always. it depends on how the pulleys are hooked up.
Ronald Logan
Ronald Logan 5 måneder siden
why no mention of the relative diameters of the pulley's ? It makes no difference ? I think not.
Michel van Biezen
Michel van Biezen 5 måneder siden
The diameters don't matter (up to a point of course). The goal is to keep the rope vertical and that is how the diameters are chosen.
Lokgator Industrial Fasteners
great video for internal training
Michel van Biezen
Michel van Biezen 5 måneder siden
Glad it was helpful!
Siren
Siren 5 måneder siden
I... I might actually have a chance of passing my ASVAB test now... thank you so much sir, this is amazing
Michel van Biezen
Michel van Biezen 5 måneder siden
All the best
Joachim Deschner
Joachim Deschner 5 måneder siden
Then: Meh... school is boring, lets sleep. Now: Ohh let's watch a physiks class.
Oliver M
Oliver M 5 måneder siden
sameeee lol. Mostly because instead of taking classes that I'm actually interesting in like engineering and physics I am forced to take classes like Spanish and gym.
Meemanage Rajitha
Meemanage Rajitha 5 måneder siden
Thank you
Michel van Biezen
Michel van Biezen 5 måneder siden
You're welcome
Quyền Nguyễn Thế
Quyền Nguyễn Thế 5 måneder siden
awesome
kashmir pandit
kashmir pandit 5 måneder siden
great explanation ....👌
Michel van Biezen
Michel van Biezen 5 måneder siden
Thank you 😃
Prince Kumar Mishra
Prince Kumar Mishra 5 måneder siden
Thank you so much sir I got such a best knowladge here now. You are now one of the best teachers of mine. Love and respect from India.
Michel van Biezen
Michel van Biezen 5 måneder siden
Thank you and welcome to the channel
Nangial Khan
Nangial Khan 5 måneder siden
I have never seen such explaination more easier than my teacher at school In fact i did not get all of my repectable and beloved teacher
Popikawaii
Popikawaii 5 måneder siden
What is this witchcraft
ツキノワグマ
ツキノワグマ 5 måneder siden
I write this comment by using translation machine. I'm a Japanese high school student and going to take an exam next month. I like physics but I'm not good at pulley. Luckily, I can know new attitude that my schoolteacher doesn't teach by watching this video. Thank you.
Michel van Biezen
Michel van Biezen 5 måneder siden
Thank you for writing and we are glad that you find the videos helpful
Андрей Подольский
Good job, nice way
Michel van Biezen
Michel van Biezen 5 måneder siden
Thanks!
Nain Singh
Nain Singh 6 måneder siden
Explained in simple words 👌
Michel van Biezen
Michel van Biezen 6 måneder siden
Thanks a lot 😊
Saqlain Ansari
Saqlain Ansari 6 måneder siden
Can you please tell sir, how will I decide that where should I draw free body diagram...
Michel van Biezen
Michel van Biezen 6 måneder siden
You can draw a free body diagram around any part of a system. From each drawing you will gain specific information. Essentially, you draw a free body diagram around the part for which you want to define all the forces on that part.
zac h-m
zac h-m 6 måneder siden
In the first simple example does the principle of equal and opposite force not mean the that the pulling force needs to be more or they will just hold each other, ie at least 101Nm to lift the 100n ? Not qualified in any of this, just a real question of my logic?
Michel van Biezen
Michel van Biezen 6 måneder siden
Only momentarily. After the object begins to move, a force equal to the weight will pull the object up at a constant speed (Newton's first law).
Carlos crispiniano gomes dos santos
Very good, same I do speak english, understend perfectly. Congratulations.
Michel van Biezen
Michel van Biezen 6 måneder siden
Very good!
wilson oliveira
wilson oliveira 6 måneder siden
Good explanation indeed!!
Michel van Biezen
Michel van Biezen 6 måneder siden
Glad it was helpful!
S Red
S Red 6 måneder siden
great explanation. Just that you got the hook to the object in the wrong spot in the last pic :)
Maarouf
Maarouf 6 måneder siden
Black magic! :)
The Kehoe Show
The Kehoe Show 6 måneder siden
Question. The force applies to the upper support beam is still 200N for all examples? Thanks.
The Kehoe Show
The Kehoe Show 6 måneder siden
@Michel van Biezen Ah ok, so the weight being lifted plus whatever force required to lift it, dependent on number of pulleys... got it. Thanks a lot!!!
Michel van Biezen
Michel van Biezen 6 måneder siden
Only for the first example. It would be 150 N for the second, 133 N for the third, and 125 N for the fourth example.
Gamer HARSHA OP
Gamer HARSHA OP 6 måneder siden
This is the best video about pulleys
Cyrus Dariush
Cyrus Dariush 6 måneder siden
Doesn’t the diameter of pulleys have an affect as a lever to change the force required too??
Michel van Biezen
Michel van Biezen 6 måneder siden
To a point, the diameter of the pulleys do not matter much. The size is chosen to keep the ropes vertical.
Azuz Kharef
Azuz Kharef 6 måneder siden
Good
Istina Anitsi
Istina Anitsi 6 måneder siden
what about an experiment?
墨洇于水
墨洇于水 6 måneder siden
这是初中力学的知识
Guillermo Valecillo
Guillermo Valecillo 6 måneder siden
Muchas gracias excelente video con gran explicación.
Michel van Biezen
Michel van Biezen 6 måneder siden
Glad to be of help.
colin mccarthy
colin mccarthy 6 måneder siden
I studied the Mechanics of Machines in my Degree.There is your Answer.❤️❤️❤️❤️.
Ace John
Ace John 6 måneder siden
or just divide it by the number of pulleys ..just a thought.. F=W/num. of puleys
Michel van Biezen
Michel van Biezen 6 måneder siden
That doesn't always work. It depends on how they are connected.
Eugene curtis
Eugene curtis 6 måneder siden
Still seems like magic
さやこた
さやこた 6 måneder siden
今日共通テストでたな
Arun Kumar
Arun Kumar 6 måneder siden
Nicely explained, thank you.
Michel van Biezen
Michel van Biezen 6 måneder siden
You are welcome!
ぷっきゅぷっきゅ
ぷっきゅぷっきゅ 6 måneder siden
面白そうな動画なんだけど、日本語で頼む。
Cor Graveland
Cor Graveland 6 måneder siden
Awesome explanation. Makes it very easy to understand.
Gökhan Haldan
Gökhan Haldan 6 måneder siden
Şekli ortadan böl. Yük /Kuvvet kolu hariç diğer ip sayısı
Jerry Tan
Jerry Tan 6 måneder siden
I learnt this in my primary school science. Thank you my teacher! (Too bad never have a chance to use pullies even after 20 years)
Michel van Biezen
Michel van Biezen 6 måneder siden
Happy to help!
Speak Japanese In English
Speak Japanese In English 6 måneder siden
I dont understand how the 4th drawing is connected together. Oops. Never mind. I can see it better on the Advertising Sign for this video.
Kevin Crawford
Kevin Crawford 6 måneder siden
Professors be like: I'm gonna have to take a couple of points off for not putting units.
Erick Juma
Erick Juma 6 måneder siden
Nice I think it's also important to state that the friction between the pulleys and the string has been ignored.
Michel van Biezen
Michel van Biezen 6 måneder siden
That is correct
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