Mechanics of Materials: Lesson 30 - Shear Moment Diagram, Equation Method...Challenging!

[@ZeonLP]

Your teaching style is amazing. In the statics books I have read, they love to overcomplicate these things, when in reality it can be very clear and intuitive if someone explains it in such good way.

[@bobosamathcee]

Hands up for you sir. In this pandemic we need a professor like you ,👋

[@iSustainnn]

Bobo rin ako sa math pero hinding hindi susuko! haha

[@nabilabsar4237]

I love you man. You just cleared my conceptions about shear force and bending moment diagrams. May God give you good health and all the happiness you desire. Loved your videos, Thank you so much.

[@study7999]

for those who dose understand why y=9-2x.I think the best way to understand is that the x is negative in x-yplan. but we need a positive distance to compute the total force in rectangle.

[@study7999]

also, you can just use Y=2x+9, and put the negatiove sing on the x, when compute the total force area.

[@Zain69z]

Thanks But don't worry I still don't understand. It's like i have no idea what he's talking about. I remember solving equations like this one on my own but in a completely different way

[@1light4love]

🤣 Im just here for 7:35... 'and THEN what? BAM!'.... it just keeps getting better🤪🤓👍 Thanks for always clarifying my midnight Strengths HW insanity.... with smiles worth replaying.

[@manuboker1]

Wonderful solids lessons!! really taking the time to explain the problems along with a good sense of humor :))

[@busybee4762]

you are the best professor i ever had .god bless you

[@AdventuringtheWild]

Great Explaination! This actually makes so much sense now:) Thank you!

[@alishad9777]

Your videos are great Jeff! Thank you for posting. This one was tough, hopefully The exam probs aren't this hard. I could not wrap my head around the equation y=9-2x

[@ashikrahman5370]

He took (0, 0) point at B. Which makes tan(6/-3) and intercetps at 9 on Y axis.

[@roccovigorelli2322]

He tooks B as (0,0) and in the function Y=2x+9 he makes the sostitution x=-x, (as the x has to be negative in the graph) in order to find the Y required, and in this way it comes out Y=2(-x)+9

[@study7999]

I don not get it the slop should be positive when apply in math.@@ashikrahman5370

[@study7999]

Why the sositution should be x=-x. @@roccovigorelli2322

[@solomonmule3414]

my question is why did you sir have to put a negative for x @ 14:11

[@gregpechey1559]

hello did you manage to find the reason for this?

[@danielledadis]

I think it's because of his axis placement, if you go back 12:40 he puts his x-y coordinates to the right of the beam. So to find the height, you move in the negative x direction hence x is negative

[@solomonmule3414]

@@gregpechey1559 not yet

[@solomonmule3414]

@@gregpechey1559 but someone has replied what could possibly be

[@ahnaftahmid]

very good professor, thank you!

[@ramaiskandarani1456]

Can you please explain from where you got y=6/3(x)+9 I did not understand that one

[@mrperfect00720]

I think, it should be like y=6/3(x)+ 3

[@PTharat]

Haha me too. If he found X from the A part, it would be easier to understand. Another video can help...

[@lukehunter2362]

No it is correct. We are assuming the 9 is the y intercept of the equation of a line y=Mx+b. The reason it’s 6/3 is rise/run and the slope was made negative because it’s is going downward from the intercept. When you want to know if the slope is positive or negative follow the line from the intercept

[@lukehunter2362]

If we were solving the top part of the triangle the intercept would be at 3 and the slope would be a positive 2x

[@vansinhnguyen7578]

Thanks Jeff!!! Your lessons that make me recall exactly when I was in Civil class sometime in 25 years ago. Appreciated Sir.

[@eykaaaa99]

Why i sub x=6 in the moment eq i get -4.5 not zero?

[@christiancarlson227]

at 10:19 why is it fast and then slow ? It is flat and then goes down that would be slow then fast if I am not mistaken

[@christiancarlson227]

never mind. I see why I am wrong. Its how it is accumulating load not the shape of the curve

[@ksa2479]

Thanks For Ur great effort Dr.Jeff , But I think it's quite enough to Find the moment and derive the equation to get the shear force directly or integrate the shear force to find the moment.

[@arc5578]

can someone explain on how or why did he put negative on the 2x ? I'm only confuse on that part. I've been reading the comments but I seem to still not get it.

[@vikneshmaniam5618]

me too bro, isnt the slope upwards

[@leoromo74]

@@vikneshmaniam5618 Look at it like a coordinate system. On his diagram his origin is on the right side of the beam where By=14.25 points upward (14:04). The slope is indeed going up where y=2x+9. At the origin x=0, so y=9 which makes sense because the force distribution at that point is 9kN/m. The height at the other end of the beam lies on top of the negative x axis of the coordinate system (quadrant II). If the function f(x)=2x+9 and x is (-x) then y=-2x+9. I hope that makes sense

[@ericescobar5794]

Can you add this video to your statics playlist also? I didn't know about this video and had to deal with more advanced problems like this in statics. is there a video with these diagrams but with back to back triangles (both max heights at the center) on a cantilevered beam? im having trouble once i get to the second triangle.

[@johngentry29]

I have a question: At 7:35, wouldn't the shear graph drop straight down 3 kN before becoming parabolic?

[@HandNoteLala]

thank you for the lesson..the video helped me sooo much for my final exam

[@bradvincent2586]

at 14:00, how do you just switch the sign and figure out what x is... and it only gets more confusing from there. I mean, I passed calc 3 with an A and I’m not really getting this

[@marwanrababah4704]

x=0.9495 m=13.173 equation of dist. force : -2X-3 Equ. of shear: 3.75-x^2-3X Equ. of the moment: 11.25+3.75X-1.5X^2-(1/3)*X^3

[@sebastianfinn3028]

He used the right hand side of the drawing as the origin, so if you made a mirror image of the picture from the origin (so that x would be increasing from left to right), the slope would become negative. At least, that's how I reasoned it out.

[@marwanrababah4704]

@@sebastianfinn3028 thanks ! I had the same final results but with different x value Now i see why , the both methods are correct but each one uses a different reference

[@MeesBorg]

Very clear explanation, thanks for this. Can we make a formula for the whole beam or only for the part we cut? I noticed in this example that when you try to enter a value of 6 for x you get weird numbers which don't add up. I am in particular curious about this because this problem has a linear load that stops in the middle and thus these are two different loads. I can imagine when the load continued to the end 1 equation is easier.

[@gavinyu6251]

Thank you I’ve been looking for a solution for this kind of load for ages

[@JovinKimario-n5m]

thank you for the lesson

[@DazzSpace]

Awesome presentation. I like your humor. 😚

[@Ahmed-Afkir]

Good work Dr Hanson

[@desalegnhunduma1968]

Interesting lecture.

[@solomon12366]

Hi Jeff. Im confused about something. Why is the bending moment diagram sloping up instead of down after the 3 meter mark? I get the straight line from 0 to 3 (first half) but why curve the line upwards on the bending moment diagram?

[@bhamuzasiphamandla5560]

thank you sir !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! Take me home :) :) :)

[@سيفالدينسعدي_مدني]

Think so much from UN. OF Mosul

[@justasketch1427]

how did he get the rise=6 and run=3??

[@solomonmule3414]

he concentrated on the triangle,,,,,,,,for the triangle,the height is 9-3=6 and the breadth =3

[@mudauwashington-zq3ed]

How do I know that I'm turning my diagram at a right point??

[@1234jhanson]

Just watch the direction of the arrows on the graph above the one you’re working on. Not sure if this answers your question…

[@jacoblugtu7205]

Why is the equation 9-x^2?

[@GhostTheGSD]

The rectangle (9-2x^2) plus the triangle (x^2)

[@ellyvatedaf]

The load backpack is such a cute concept lol

[@anoudta1466]

How did the rise = 6? isn't it 9?

[@Stricknine47]

It went from 3 to 9, so the rise was 6.

[@tatjoni]

Might want to mention the limits for x where functions apply?

[@mrtylmz2209]

According to the previous lesson (24), I use the semi parabolic area formula to calculate the x and I found x and M as 1.5625 and 14.8438, respectively. I think the semi parabolic area equation is not suitable for that kind of curve. (Please correct me if I'm wrong)

[@marwanrababah4704]

x=0.9495 m=13.173 equation of dist. force : -2X-3 Equ. of shear: 3.75-x^2-3X Equ. of the moment: 11.25+3.75X-1.5X^2-(1/3)*X^3

[@DOBLYyyy]

why when i put 6 for the x in the moment equation it doesn't give me zero. what did i do wrong?

[@nankundaarnold6486]

absolutely and completely helpful (kowtow)

[@WonderingNobody]

Sir could you please make video on finding Shear force and Moment using heavy side notation or step function ? And with different types of distributed forces like UDL and UVL as well as support ?

[@notyourbusiness8672]

Freshman humor 🙄

[@franciscomellone1041]

dM(x)/dx should be V. in this case is -V. Am I wrong?

[@jerrysmith9780]

When I integrate V, I get -M, is that what you get too? -11.25? It should be +11.25, right?

[@xi.mipa.1_farisalfian222]

love u man

[@iqtime1400]

אתה באמת מלך

[@robiyonas1401]

thank you for re uploading

[@RK-tr7wo]

Great example sir !!

[@barunrahiroy3687]

A great one indeed 👍

[@jerrysmith9780]

Can someone assist here please. When I integrate V, I get -M. Any idea what I did wrong?

[@tiaanjansevanrensburg2762]

#1 Professor

[@IddSeleman]

How to draw it by integration method

[@karanchowdhary5969]

Nice teacher

[@matthewbarnes-webb9320]

when I tell you I got disappointed when you didn't call the 3.75kn force a van Halen force :)

[@sunmichoi6888]

Thank you !!!!!

[@fretekeste]

Thank you sir

[@rezafatahi1948]

Good

[@Adam_mohammed_]

Who noticed that the video is coming up to 4K hhhhhhh nice!

[@angeloumagboo8848]

thank youuuu

[@aryanndharamsey2064]

Why doesn't the total area for the v diagram equal 0

[@borisbesovic5549]

Diagram moment go down.

[@barunrahiroy3687]

It seems the shear diagram is incorrect if x=2.05 from B . It should be modified later on it gave me a lot of confusion.

[@brucelee1048]

for practice i decided to find x on the other side of the beam and i got 0.95 which is the same, so I believe it is correct

[@marwanrababah4704]

@@brucelee1048 I had that too! Thanks

[@Smileyyyy1806]

Take me home to the place where shear equals zero. Now listen on Spotify :P

[@erwinasesmanalastas6982]

This where i am good about ... Not water.

[@drastipatel9558]

goat

[@IddSeleman]

How to draw it by integration method