Mechanical Engineering: Ch 13: Virtual Work Applications (6 of 39) Partially Constraint Structure

[@Zeusbeer]

I love you, my statics teacher was explaining small angle approximations but I didn't realise that you can also just take the derivative of x with respect to theta and it just magically works

[@MichelvanBiezen]

Glad to be of help.

[@kaursingh637]

SIR -U R THE BEST ON EVERY TOPIC - U THE BEST ON VIRTUAL WORK -THANK U SIR

[@chandankumar-sj5se]

sir, you are doing noble work.please upload more video on virtual work problems.

[@MichelvanBiezen]

It is on the plan (among many other topics we are trying to cover).

[@Step_Up001]

Sir your concept and way of teaching is real very nice

[@samireddioui3590]

Hello sir thank you for your effort but shouldnt it be a negative value ?

[@JanYellow]

Yes, as far as I understand it, on minute 5:49 a minus sign is missed.

[@JanYellow]

Hence, the result should be negative, which makes sense due to the direction of R.

[@bartvrhijn]

Great video! One thing that is unclear to me is that dy = (negative) - L*sin(theta) dtheta, while it is substituted as a positive value. The final answer in this video is a positive value, which is intuitive correct. So this is odd.

[@bartvrhijn]

To answer myself: It is the dot product between the two vectors.

[@MichelvanBiezen]

Correct. When you take the dot product of 2 vectors, you multiply the magnitudes of each of the vectors, and magnitudes of vectors cannot be negative.

[@kelvaabacar4411]

I appreciate your explanation. Thank you so much

[@MichelvanBiezen]

You are welcome!

[@421-18c]

best professor

[@swimcoach3702]

In canceling out L and dtheta do we have to stipulate that neither of them is equal to zero? I've noticed that most instructors are pretty fast and loose with canceling out without this stipulation. Is it really necessary to point out, for example, that L is obviously not zero and dtheta is not zero because of its nature? Kind of nitpicky, but I've always wondered this.

[@MichelvanBiezen]

That is why we have mathematicians to keep us honest. However if we know that L and d theta are not zero, then there is no need to make the stipulation.

[@vickuscala6271]

gracias profesor ,y siga haciendo mas vídeos sobre trabajo virtual ,saludos desde la paz BOLIVIA

[@MichelvanBiezen]

Welcome to the channel!

[@anthonysawaya6142]

hello do you have any videos about shear and moment diagrams

[@SkanderTALEBHACINE]

Hello, why X0=2*L*sin(thêta) ? the structure is not symetric?! thanks

[@MichelvanBiezen]

The two beams have the same length. Therefore the left side is symmetric with the right side.

[@ferhatpolat281]

dy is equal to -L times sin bla bla. SO it must be R= -F/2*tan

[@appelbanaan3913]

@ferhat polat No his answer is correct. The vector force F is equal to -F in the y direction, so - and - equals +. Secondly the force R can't be negative as this would result in a force oriented to the right in point B, in which case the object would not be in equilibrium.

[@mohamedsr5817]

@@appelbanaan3913 Nope, the force has to be negative and the F which is shown is not a vector.

[@ayadal-arefi3723]

I LOVED THAT BUT I think there was a mistake with thhe signs - and +

[@IIM_ayushgandhi]

Why moment at the pin joint 'A' not taken into consideration?

[@evolvingnoobs_aoe3428]

Moment has no role in the problem with virtual work. Only forces that contribute to a possible change in (virtual) displacement are considered. Any type of force acting on the Pin joint will not cause displacement at A. Hence even if u consider, it will multiply with the displacement at A (which is zero) and becomes zero.

[@zhuangadam9517]

A is pinned, so it does not have reaction moment so to say to do work like M*dtheta

[@MohamedAdel-ik2fy]

Thank you ❤

[@alijoueizadeh8477]

Thank you sir!

[@MichelvanBiezen]

You are welcome!

[@pinturajak9590]

Value must be negative

[@PICZ7]

The final value must be negative

[@-Teus-]

I love you