Well work done is the area under the curve. If the curve is regular then you might have a formula you can use. Otherwise its a case of adding up the squares (if its plotted on graph paper).
Young's Modulus will apply to anything where stress is proportional to strain. So if the proportionate extension is related to the pressure or stress (force over area).
Well you could watch my 44 A Level Physics revision videos (assuming you are doing A levels or equivalent exams) but they are really only revision videos and can't replace the original tuition. Good luck with the exam.
Hooke's Law so clearly explained, and the associated physics too. Thank you. Always interested in Hooke's Law. Robert Hooke is part of our family tree!!
Well for A Level physics its probably sufficient to say that the bonds within the crystal structure are atomic or molecular. But at an engineering level it all gets much more complex. It's not something I've studied at that level.
00:00 Hooke's law F=kx 06:23 Stress and Strain Stress(tensile strength)=F/A Strain=x/l W=1/2 Fx= (kx^2)/2 12:53 Young's Modulus E=Stress/Strain=Fx/lA Energy in stressed material = 1/2 (stress)* strain or the area under the stress to strain graph
I guess the point they were making is that if the material returns to its original state then the material was being stretched within its elastic limit. ie it had not gone beyond that point in which case it would not have done so. A spring can be loaded and unloaded and still obey F=kx as long as you always keep within the elastic limit. But if the spring gets deformed with too heavy a load then the F=kx rule will no longer apply.
I think you've answered your own question. Wk = Fx when the force is constant. If the force varies (as it does with Hooke's law) then you have to integrate each element of F dx to find total work done. So Wk = Integral F dx. In the case of Hooke's law for, say, a spring the force varies linearly with x (since F=kx). So you get a straight line relationship between F and x. The integral in this case is just the area of the triangle under that curve, which is half the base times the height ie Fx/2.
In the case of a spring, the extension (x) is the distance between the mean position and the extended position. Force = kx where k is the spring constant. But if you consider a spring oscillating then the force is constantly varying since it is proportional to the extension which itself is constantly varying.
Elastic - a stretched material will return to original shape cos atoms can be pulled apart up to a limit and the move back to equilibrium position when load removed. Plastic - stretch leads to permanent deformation - atoms dont return to original position. You may need to look up how atoms are organised in metals, ceramics, polymers and combinations.
You can't calculate tensile strength from info in this video. Tensile strength is the maximum stress that a material can withstand while being stretched or pulled before deforming. It is usually found by performing a tensile test and recording the stress versus strain. Tensile strength is defined as a stress, which is measured as force per unit area.
Stress = f/a will always be true but in the case of a spring it is very complicated and not much use. In the case of a wire hanging vertically with a weight F=mg on the end, then the relevant area is the cross sectional area of the wire. But for a spring the wire is coiled and it would be difficult to assess the cross sectional area to which the force applied.
I am no expert on this but it is to do with molecular structures. During the elastic stretching the molecular bonds are stretched but the structure remains in tact. The yield point arises when the bonds start to break and the material cannot then return to its original state.
Hi. Hooke's Law doesn't apply on an atomic scale because of Heisenberg's uncertainty principle. At the atomic scale all measurements are uncertain. But atomic vibrations can be thought of as similar to the simple harmonic vibrations of a spring as in my videos on SHM.
K is the spring constant such that F = KX, where F is the force and X is the extension. Stress is force over area. Strain is extension over original length. From that you should be able to derive an equation for K.
Not uniquely. The material in the A Level Physics playlist covers the main material in the Edexcel, AQA A/B and OCR A/B courses except for some biophysics which I have not covered.
Thanks for kind comment. Young's modulus is defined as stress over strain which is pressure (F/A) divided by strain (extension over original length). So E = F/A / x/l which can be rearranged to E = Fl/Ax
It will certainly distort if you crush it. Not sure if that is "crossing the elastic limit" since that term is usually reserved for over-stretching the spring.
You are a ledge, I have been studying this in science for weeks and my teacher does not explain shit all, I've just learned how to do this in a quarter of an hour. Cheers pal, have a nice day ;)
At 13:55, as I indicated in my reply to an earlier comment, I was actually just establishing the dimensionality. E = stress/strain = F/A / x/L = FL/Ax = units of work/energy / units of volume - hence energy per unit volume. The graph at 15:30 better sets out your point. The energy per unit volume stored in a stretched wire is 0.5 x stress x strain = 0.5 (F/A) (x/L).
I love learning more about math and physics! I struggle with other topics so focussing on my passions in my spare time will help me become a better phycisist in future.
Probably one of the best videos I've seen regarding the topic of stress-strain, springs, etc. not only from a practical standpoint but from an experimental standpoint as well. DrPhysics, thank you for supplying the community with multi-faceted ways of thinking that is applicable not only to students but also to potential real-world applications in a work environment as well.
Well I assume that the "bar" you refer to is capable of being stretched - so is in the form of a wire. Measure length of wire and diameter (from which cross sectional area can be calculated). Suspend wire from a suitable fixed point. Hang weights on the wire and measure the extension for each weight (but dont go beyond elastic limit). Plot Force/Area against extension/ original length. The slope is Young's Modulus (ie F/A / x/l)
You are right that the limit of proportionality comes first and is usually closely followed by the elastic limit. Hooke's law still applies at the limit of P, but if you go beyond the elastic limit then the material will be permanently stretched/deformed. There is some material on Work, Energy and Power at the back end of the vid on "Classical Mechanics - A Level Physics"
@Dr.PhysicsA,Do have a video for the Analysing Forces in Equilibrium? I need you teach how me how to form a diagram to make it easier so that I can know which SIN,COS or TAN I need to applied.
Hi there, this was a very clear and informative video although i would like to add that you could use searle's apparatus to measure the young modulus of a wire. This involves adding a second wire parallel to the test wire, the second wire acts as a control wire where by any changes in temperature do not affect the end results due to the addition of the second wire. Also a vernier scale could be installed between the two wires which you use to gauge how far the test wire has extended as opposed to the control. Also i think that you need to explain the fact that the young modulus which can be calculate graphically only applies to the straight portion of the stress/strain graph. Young modulus can only be measured within the limits of proportionality. Thanks for making the video, i just wanted to add a little of my knowledge just to clarify a few things.
Dr.PhysicsA can you tell me how i can find out the cross sectional area and tension in the wire in young modules. if you have a video can you please put the link on the message board.
@Drphysics:I said how do i get an a in the exams, I'm not worried about course-work as it is only 15% and could your videos are superfast I cant follow them, please make it slower. Thanx
Strictly it is Energy per unit volume = 1/2 * stress * strain. On your second point I was actually establishing the dimensionality. E = stress/strain = F/A / x/L = FL/Ax = units of work/energy / units of volume - hence energy per unit volume.
You find the cross-sectional area by measuring it using a device which measures the circumference accurately. The tension will usually just be the weight applied to the wire which you will usually determined.
My A level playlist covers material for OCR A and B, AQA and Edexcel, with some CIE as well. I can't really tell you how to convert a C to an A other than to go thro the material thoroughly and perhaps practice exam questions, examples of which you can find online. All good wishes for the exam.
Well the modulus of elasticity is usually the same as Young's modulus which is stress/strain. Stress is F/A and strain is x/L. So E = F/A / x/L = FL/xA. So F/A = Ex/L. That means that T in your equation must equate to Stress.
Mahmoud Matar force*distance = work done in general when moving something, or in this case stretching/compressing. Here force isn't constant so less work will be done each moment when you start to stretch something compared to when its almost fully stretched. the power (work done per second) changes so average amount of energy transfer is needed to give an overall value. that probably doesn't help but its kind of hard to explain
Shon Wuls Oh I think I got what you mean, if the force is constant, at that time work=force*distance, but if the force is varying throughout the stretch/compression, then we take the average force isn't it?
Shon Wuls that means that the more it strerches, the more force you need to apply to stretch it more, and that's principally the reason why the force varies?
So cool, really good video, I think you missed 2 points: 1- you explained stress and strain and have not include them in the video title 2- you missed using the symbols for both stress and strain which are sigma and epsilon respectively. Thanks
Wow you've helped me A LOT. My script at university is absolutely terrible comparing to this :) saved me for today's lab, as I was really struggling to get it all :)
I've spent 6 weeks with my teacher rabbiting on at me about Young's Modulus but she never once said what it actually is. Thanks to this I finally understand how simple it is! This is an excellent video, thank you!
Elastic limit is when the material stops behaving elastically and begins behaving plastically - from here onwards it would no longer return to it's original length. Yield point is when the material suddenly starts to stretch without any extra load.
Hi, excellent videos, I follow all your work. Small point, (~16.29) I don't think the area under a stress strain graph gives you stored energy. The units will be wrong. Only the area under a force extension graph give you the energy stored. Let me know what you think.
You said that the young modulus is the work done per stretched volume, and work done is equal to the energy transformed, so basically the energy per stretched volume is equal to the gradient of the stress vs strain graph, so why are we taking the area?
Hi, I understand completly these operations and concepts. However, what I seem not to find/understand is how can I calculate the Young's Modulus if my input data has many times given Tensile Strength values and Tensile Elongation (in %) Would these "Strangth and Elongation" be considered "Stress" and "Strain" respectively? I am confused and don't know if i am doing it right.
Since,the change in length(strain)depends upon the force(stress),wouldn't it be more appropriate to choose stress along x-axis and strain along y-axis?
Hooks law and youngs modules at the level of quantum physics become physical chemistry of properties of material at 4 basic level interactive forces ???😀😀😀😀😀
Veljko Milković, an academic and inventor from Novi Sad, has done something great that has not been done by any Serbian inventor before. Milković invention of the mechanical oscillator is widely used worldwide, a testament to the fact that over 500 foreign companies use, sell and manufacture pendulum-based machines used in the heavy industry. The purpose of the two-stage meganic oscillator is multifaceted, because the character of the machine (two-arm lever with pendulum) allows its use as a press, water pumps, compressor, crusher, power generator, mini power plants.
I didn't get the end where it says kx^2/2 is basically the area under a triangle as its compared to 1/2 *stress*strain (which definitely is the area of a triangle) however kx^2/2 isn't the area of a triangle, as it contains square, it should be 1/2*k*x. I am confused, I know I'm wrong I just need an explanation. Thanks.
We need good educational Films on youtube like these films,because it is revision for me. My thanks go's to the lecturer & person who produced the films and also youtube.''Thank's''.
Hi, when I learned this I was taught that when you do an experiment to plot a stress-strain graph, the area does change (particularly during plastic deformation when the material starts to neck). I don't really fully understand this so I could be wrong.
4:30 - wouldn't it be better to describe it as the limit of proportionality rather than elastic limit? The material still exhibits elastic properties at the limit of proportionality - the only difference being that force exerted doesn't equal the extension. I've always learnt them as two different points, but I might be wrong. Thought I'd make a point of it. Thanks.
if i didn't understand wrong, young's modulus is actually the work done to per unit volume which is streching . But if i think of a spring, what is the volume? spring would have a free space inside the helix shape unlike a wire. is it still consistent?
I have an elastic tube, and inside the tube i put wather uder diffrent pression to observe deformation of the tube. How can i compute Young modulus, knowing the pressures and the deformation of tube.
I think you made a little mistake there when you said that the point was elastic limit. It is actually considered to be the limit of proportionality as after that point when more masses are added it does not obey hookes law and hence there's no "proportional" extension. However if the masses are removed it will comeback to its original position. But after the limit of proportionality comes the elastic limit, after this point even if the masses are removed the spring will not go back to its original position. :)
Hello! I am a bit confused as to why there are two equations for work done? I got wk=F*x. But then you said that the average wk = (F/2)*x. Now again this sort of makes sense to me, in that the average force would be F/2 if the force was gradually increased on a period of time from 0 to max F. But I guess what I'm asking is what is the significance of each of the two and what applications would you have to use and and not the other? Thanks :).
Hi. In my Mechanics 3 (Edexcel) textbook it says that Hookes law is: T = (Lambda / L)x, where Lambda is the modulus of elasticity, L is original length and x is the extension. The book describes Lambda as the modulus of elasticity. Does this mean that lambda is Young's Modulus E? Or is lambda EA, where A is the cross sectional area? I am quite confused because wikipedia says that the modulus of elasticity is stress/strain, which is E, however I think it's wrong. Thanks in advance
So, is Hooke's law a law stating that the stress applied to a material is proportional to the strain on the material, or is it a law stating that the extension of the spring is proportional to the force stretching it (provided the elastic limit of the spring is not exceeded) or both?
@DrPhysicsA: Dr, in the end you say that energy stored = half * stress * strain . But that has the units of Pascals. So it's not dimensionally correct. I also didn't understand how you substituted FL with Wk in the equation for Young's modulus. F is not moving through a distance L; L is fixed.
@DrPhysicsA i am doing kevlar for a physics project and was wandering how to explain the fact the kevlar has a youngs modulus yet its is flexible. I thought that this would be contradictory due to youngs modulus being a measure of stiffness. Any help would be greatly appreciated thanks.
Hello, firstly can I just thanks for putting up these videos. They've helped me enormously with AS Physics so far. At 4:28 you call the point illustrated with an arrow the elastic limit. Isn't this the limit of proportionality? I thought the elastic limit came after the limit of proportionality. On another note, are you planning to publish any videos on work,energy and power? Cheers.
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Very clear descriptions here that have really helped the students I teach. Thanks.
A Level Physics Online lol u copy him?
it is rare to see one legend commenting on the video of another
j lee - these videos are designed for the syllabuses of AQA, OCR, Edexcel and CIE. Not all of them will be relevant for each course.
DrPhysicsA you should make a patreon!
DrPhysicsA
DrPhysicsA-S/TG
Sorry - don't know. My vids are intended to cover the broad A level material of the main A Level courses.
Well work done is the area under the curve. If the curve is regular then you might have a formula you can use. Otherwise its a case of adding up the squares (if its plotted on graph paper).
Young's Modulus will apply to anything where stress is proportional to strain. So if the proportionate extension is related to the pressure or stress (force over area).
Stress is proportional to strain.
Well you could watch my 44 A Level Physics revision videos (assuming you are doing A levels or equivalent exams) but they are really only revision videos and can't replace the original tuition. Good luck with the exam.
Hooke's Law so clearly explained, and the associated physics too. Thank you.
Always interested in Hooke's Law. Robert Hooke is part of our family tree!!
ohh really
👌🏻😂😂
Yes. The SI units use kg, m and sec. So if a measurement is in mm you need to convert it to m.
Wk is Fx/2
But F is kx by Hookes Law
So E = Wk = kx2/2
Well for A Level physics its probably sufficient to say that the bonds within the crystal structure are atomic or molecular. But at an engineering level it all gets much more complex. It's not something I've studied at that level.
00:00 Hooke's law
F=kx
06:23 Stress and Strain
Stress(tensile strength)=F/A
Strain=x/l
W=1/2 Fx= (kx^2)/2
12:53 Young's Modulus
E=Stress/Strain=Fx/lA
Energy in stressed material = 1/2 (stress)* strain or the area under the stress to strain graph
QUESTION:
why does the yield point (the point at which the material stretches with constant or reduced load) occur?
Good. Hope the exam went well.
I guess the point they were making is that if the material returns to its original state then the material was being stretched within its elastic limit. ie it had not gone beyond that point in which case it would not have done so. A spring can be loaded and unloaded and still obey F=kx as long as you always keep within the elastic limit. But if the spring gets deformed with too heavy a load then the F=kx rule will no longer apply.
I think you've answered your own question. Wk = Fx when the force is constant. If the force varies (as it does with Hooke's law) then you have to integrate each element of F dx to find total work done. So Wk = Integral F dx. In the case of Hooke's law for, say, a spring the force varies linearly with x (since F=kx). So you get a straight line relationship between F and x. The integral in this case is just the area of the triangle under that curve, which is half the base times the height ie Fx/2.
In the case of a spring, the extension (x) is the distance between the mean position and the extended position. Force = kx where k is the spring constant. But if you consider a spring oscillating then the force is constantly varying since it is proportional to the extension which itself is constantly varying.
Elastic - a stretched material will return to original shape cos atoms can be pulled apart up to a limit and the move back to equilibrium position when load removed.
Plastic - stretch leads to permanent deformation - atoms dont return to original position.
You may need to look up how atoms are organised in metals, ceramics, polymers and combinations.
You can't calculate tensile strength from info in this video. Tensile strength is the maximum stress that a material can withstand while being stretched or pulled before deforming. It is usually found by performing a tensile test and recording the stress versus strain. Tensile strength is defined as a stress, which is measured as force per unit area.
Stress = f/a will always be true but in the case of a spring it is very complicated and not much use. In the case of a wire hanging vertically with a weight F=mg on the end, then the relevant area is the cross sectional area of the wire. But for a spring the wire is coiled and it would be difficult to assess the cross sectional area to which the force applied.
I am no expert on this but it is to do with molecular structures. During the elastic stretching the molecular bonds are stretched but the structure remains in tact. The yield point arises when the bonds start to break and the material cannot then return to its original state.
Hi. Hooke's Law doesn't apply on an atomic scale because of Heisenberg's uncertainty principle. At the atomic scale all measurements are uncertain. But atomic vibrations can be thought of as similar to the simple harmonic vibrations of a spring as in my videos on SHM.
K is the spring constant such that F = KX, where F is the force and X is the extension. Stress is force over area. Strain is extension over original length. From that you should be able to derive an equation for K.
Not uniquely. The material in the A Level Physics playlist covers the main material in the Edexcel, AQA A/B and OCR A/B courses except for some biophysics which I have not covered.
Thanks for kind comment. Young's modulus is defined as stress over strain which is pressure (F/A) divided by strain (extension over original length).
So E = F/A / x/l which can be rearranged to E = Fl/Ax
It will certainly distort if you crush it. Not sure if that is "crossing the elastic limit" since that term is usually reserved for over-stretching the spring.
Congratulations. Have a great time at uni.
The practical aspects determine whether a material will be malleable and ductile or whether it is brittle or plastic.
You are a ledge, I have been studying this in science for weeks and my teacher does not explain shit all, I've just learned how to do this in a quarter of an hour. Cheers pal, have a nice day ;)
At 13:55, as I indicated in my reply to an earlier comment, I was actually just establishing the dimensionality. E = stress/strain = F/A / x/L = FL/Ax = units of work/energy / units of volume - hence energy per unit volume. The graph at 15:30 better sets out your point. The energy per unit volume stored in a stretched wire is 0.5 x stress x strain = 0.5 (F/A) (x/L).
Apparently I sound like Tont Robinson and Bruce Forsyth. Sounds good to me.
Apparently I sound like Tont Robinson and Bruce Forsyth. Sounds good to me.
How I wish you were here in January of 2012, but hey, Thank you so much, I'll finally be acing physics2 this time around!
I love learning more about math and physics! I struggle with other topics so focussing on my passions in my spare time will help me become a better phycisist in future.
Probably one of the best videos I've seen regarding the topic of stress-strain, springs, etc. not only from a practical standpoint but from an experimental standpoint as well. DrPhysics, thank you for supplying the community with multi-faceted ways of thinking that is applicable not only to students but also to potential real-world applications in a work environment as well.
Well I assume that the "bar" you refer to is capable of being stretched - so is in the form of a wire. Measure length of wire and diameter (from which cross sectional area can be calculated). Suspend wire from a suitable fixed point. Hang weights on the wire and measure the extension for each weight (but dont go beyond elastic limit). Plot Force/Area against extension/ original length. The slope is Young's Modulus (ie F/A / x/l)
You are right that the limit of proportionality comes first and is usually closely followed by the elastic limit. Hooke's law still applies at the limit of P, but if you go beyond the elastic limit then the material will be permanently stretched/deformed. There is some material on Work, Energy and Power at the back end of the vid on "Classical Mechanics - A Level Physics"
@Dr.PhysicsA,Do have a video for the Analysing Forces in Equilibrium? I need you teach how me how to form a diagram to make it easier so that I can know which SIN,COS or TAN I need to applied.
Hi there, this was a very clear and informative video although i would like to add that you could use searle's apparatus to measure the young modulus of a wire. This involves adding a second wire parallel to the test wire, the second wire acts as a control wire where by any changes in temperature do not affect the end results due to the addition of the second wire. Also a vernier scale could be installed between the two wires which you use to gauge how far the test wire has extended as opposed to the control. Also i think that you need to explain the fact that the young modulus which can be calculate graphically only applies to the straight portion of the stress/strain graph. Young modulus can only be measured within the limits of proportionality. Thanks for making the video, i just wanted to add a little of my knowledge just to clarify a few things.
Dr.PhysicsA can you tell me how i can find out the cross sectional area and tension in the wire in young modules.
if you have a video can you please put the link on the message board.
@Drphysics:I said how do i get an a in the exams, I'm not worried about course-work as it is only 15% and could your videos are superfast I cant follow them, please make it slower. Thanx
Strictly it is Energy per unit volume = 1/2 * stress * strain.
On your second point I was actually establishing the dimensionality. E = stress/strain = F/A / x/L = FL/Ax = units of work/energy / units of volume - hence energy per unit volume.
I hope I said that Young's modulus E was the gradient of the graph; that is stress is divided by strain.
Man your amazing at teaching physics, your videos always helped me and friends a lot !!!!
You find the cross-sectional area by measuring it using a device which measures the circumference accurately. The tension will usually just be the weight applied to the wire which you will usually determined.
It's this time of the year again :D
My A level playlist covers material for OCR A and B, AQA and Edexcel, with some CIE as well. I can't really tell you how to convert a C to an A other than to go thro the material thoroughly and perhaps practice exam questions, examples of which you can find online. All good wishes for the exam.
Well the modulus of elasticity is usually the same as Young's modulus which is stress/strain. Stress is F/A and strain is x/L. So E = F/A / x/L = FL/xA. So F/A = Ex/L. That means that T in your equation must equate to Stress.
My Hodder Education Edexcel AS Physics book and the exam I sat for the Materials exam last week would disagree.
You helped me loads on my way to an A overall in physics and an A* in physics5!!! Got into university :D:D:D
simple,clear amazing videos,very useful for the beginner, thnks you.
I didn't understand why we take the average force?
Mahmoud Matar force*distance = work done in general when moving something, or in this case stretching/compressing. Here force isn't constant so less work will be done each moment when you start to stretch something compared to when its almost fully stretched. the power (work done per second) changes so average amount of energy transfer is needed to give an overall value.
that probably doesn't help but its kind of hard to explain
Shon Wuls Oh I think I got what you mean, if the force is constant, at that time work=force*distance, but if the force is varying throughout the stretch/compression, then we take the average force isn't it?
Mahmoud Matar yeah, but force will always be varying because more force is required each moment when extension is longer as F=kx
Shon Wuls that means that the more it strerches, the more force you need to apply to stretch it more, and that's principally the reason why the force varies?
Mahmoud Matar exactly that
So cool, really good video, I think you missed 2 points:
1- you explained stress and strain and have not include them in the video title
2- you missed using the symbols for both stress and strain which are sigma and epsilon respectively.
Thanks
Abd Alkader Abdeen Agha f that’s not really necessary in understanding the concept the only symbols truly needed is the SI units
I have created 2 playlists for A-level Physics for Edexcel, they are Paper 1 and Paper 2 make sure to check them out.
o mirza but aren’t those for A2 and this one’s for AS, right?
Wow you've helped me A LOT. My script at university is absolutely terrible comparing to this :) saved me for today's lab, as I was really struggling to get it all :)
You may find something helpful in my video on Momentum in 2D - A Level Physics
Young's modulus relates stress to strain. Hookes Law relates force to extension.
The units of Young's Modulus are indeed N/m^2 (ie the units of pressure).
thank you very very much,sir.I am the best physic student in my class right now.I'm truly appreciate your work.
I've spent 6 weeks with my teacher rabbiting on at me about Young's Modulus but she never once said what it actually is. Thanks to this I finally understand how simple it is! This is an excellent video, thank you!
It's 11 years later, how are you now
@@Shalie7506 would you believe it, I took a career in teaching myself
your videos are pulling through my a-levels, keep it up!
@DRPhysicsA Is this OCR A please reply asap !!!!
Could you tell me the difference between elastic limit and yield point
Elastic limit is when the material stops behaving elastically and begins behaving plastically - from here onwards it would no longer return to it's original length.
Yield point is when the material suddenly starts to stretch without any extra load.
I have never seen anyone write "x" like you lol
Hi, excellent videos, I follow all your work. Small point, (~16.29) I don't think the area under a stress strain graph gives you stored energy. The units will be wrong. Only the area under a force extension graph give you the energy stored. Let me know what you think.
You are right. It's actually the strain energy per unit volume.
why are you even watching this?
***** not you...
You said that the young modulus is the work done per stretched volume, and work done is equal to the energy transformed, so basically the energy per stretched volume is equal to the gradient of the stress vs strain graph, so why are we taking the area?
thanks a lot sir........u are just brilliant sir,u r doing a great job for students like us....thanks once again sir
Good luck to everyone on their January exams tomorrow.
Hi, I understand completly these operations and concepts. However, what I seem not to find/understand is how can I calculate the Young's Modulus if my input data has many times given Tensile Strength values and Tensile Elongation (in %)
Would these "Strangth and Elongation" be considered "Stress" and "Strain" respectively?
I am confused and don't know if i am doing it right.
I may not fail Physics thank you so much!
Since,the change in length(strain)depends upon the force(stress),wouldn't it be more appropriate to choose stress along x-axis and strain along y-axis?
Hooks law and youngs modules at the level of quantum physics become physical chemistry of properties of material at 4 basic level interactive forces ???😀😀😀😀😀
Veljko Milković, an academic and inventor from Novi Sad, has done something great that has not been done by any Serbian inventor before.
Milković invention of the mechanical oscillator is widely used worldwide, a testament to the fact that over 500 foreign companies use, sell and manufacture pendulum-based machines used in the heavy industry.
The purpose of the two-stage meganic oscillator is multifaceted, because the character of the machine (two-arm lever with pendulum) allows its use as a press, water pumps, compressor, crusher, power generator, mini power plants.
I didn't get the end where it says kx^2/2 is basically the area under a triangle as its compared to 1/2 *stress*strain (which definitely is the area of a triangle) however kx^2/2 isn't the area of a triangle, as it contains square, it should be 1/2*k*x. I am confused, I know I'm wrong I just need an explanation. Thanks.
Stress and strain can't be reused in other uses for which they are always in use of chemical reactions.
Thanks.
Thanks.
We need good educational Films on youtube like these films,because it is revision for me. My thanks go's to the lecturer & person who produced the films and also youtube.''Thank's''.
Reasonably comprehensive and comprehendible, but not especially compelling or advanced. Worth watching
thank you :D you saved my life
Very Very Interesting fact about Young modulus = Work/volume. I did learn something new. thank you .
Hi, when I learned this I was taught that when you do an experiment to plot a stress-strain graph, the area does change (particularly during plastic deformation when the material starts to neck). I don't really fully understand this so I could be wrong.
4:30 - wouldn't it be better to describe it as the limit of proportionality rather than elastic limit? The material still exhibits elastic properties at the limit of proportionality - the only difference being that force exerted doesn't equal the extension. I've always learnt them as two different points, but I might be wrong. Thought I'd make a point of it. Thanks.
Thank you sir. Brilliant explanation!
if i didn't understand wrong, young's modulus is actually the work done to per unit volume which is streching . But if i think of a spring, what is the volume? spring would have a free space inside the helix shape unlike a wire. is it still consistent?
I have an elastic tube, and inside the tube i put wather uder diffrent pression to observe deformation of the tube. How can i compute Young modulus, knowing the pressures and the deformation of tube.
So helpful. Thanks so much
th-cam.com/video/vFDMaHQ4kW8/w-d-xo.html ..👍
How do we come to know the exact value of yield stress of a material???
Because it is difficult to find the actual point when the yielding starts???
the books i am using for studies are stating that 1Gpa= 1x10^3 N/mm^2 i am confused
I think you made a little mistake there when you said that the point was elastic limit. It is actually considered to be the limit of proportionality as after that point when more masses are added it does not obey hookes law and hence there's no "proportional" extension. However if the masses are removed it will comeback to its original position.
But after the limit of proportionality comes the elastic limit, after this point even if the masses are removed the spring will not go back to its original position. :)
Ples I want a lesson on the calculations on heat energy, specific heat energy, latent heat of fusion and vaporization
does the spring constant K equals to the gradient on the force and extension graph??? @drphysicsA
If force,F is applied on both end of wire what will be the equation of young's modules?
Hello! I am a bit confused as to why there are two equations for work done? I got wk=F*x. But then you said that the average wk = (F/2)*x. Now again this sort of makes sense to me, in that the average force would be F/2 if the force was gradually increased on a period of time from 0 to max F. But I guess what I'm asking is what is the significance of each of the two and what applications would you have to use and and not the other? Thanks :).
Hi. In my Mechanics 3 (Edexcel) textbook it says that Hookes law is: T = (Lambda / L)x, where Lambda is the modulus of elasticity, L is original length and x is the extension. The book describes Lambda as the modulus of elasticity. Does this mean that lambda is Young's Modulus E? Or is lambda EA, where A is the cross sectional area? I am quite confused because wikipedia says that the modulus of elasticity is stress/strain, which is E, however I think it's wrong. Thanks in advance
This is extremely helpful, thank you
So, is Hooke's law a law stating that the stress applied to a material is proportional to the strain on the material, or is it a law stating that the extension of the spring is proportional to the force stretching it (provided the elastic limit of the spring is not exceeded) or both?
@DrPhysicsA: Dr, in the end you say that energy stored = half * stress * strain . But that has the units of Pascals. So it's not dimensionally correct.
I also didn't understand how you substituted FL with Wk in the equation for Young's modulus. F is not moving through a distance L; L is fixed.
@DrPhysicsA i am doing kevlar for a physics project and was wandering how to explain the fact the kevlar has a youngs modulus yet its is flexible. I thought that this would be contradictory due to youngs modulus being a measure of stiffness. Any help would be greatly appreciated thanks.
Hello, firstly can I just thanks for putting up these videos. They've helped me enormously with AS Physics so far. At 4:28 you call the point illustrated with an arrow the elastic limit. Isn't this the limit of proportionality? I thought the elastic limit came after the limit of proportionality. On another note, are you planning to publish any videos on work,energy and power? Cheers.