How to solve 3D statics problems
ฝัง
- เผยแพร่เมื่อ 10 มิ.ย. 2016
- This engineering statics tutorial goes over how to solve 3D statics problems. The cross product is your friend.
If you found this video helpful, please consider supporting my work on Patreon:
/ engineer4free
Looking for more statics tutorials? Check out all of the videos that I made:
TH-cam: • Dynamics
Website: www.engineer4free.com/statics
Looking for practice problems with solutions? I also created a whole set of fully solved statics problems with step-by-step hand calculations:
www.engineer4free.com/statics...
Looking for software? I highly recommend checking out SkyCiv. They make a full suite of online structural analysis software and tools that are useful for both students and professionals, including calculators for beams, trusses, frames, moment of inertia and more. It’s great for checking your work:
bit.ly/skyciv-e4f
Lastly, don’t forget to subscribe on TH-cam and join the Engineer4Free mail list:
Subscribe: / @engineer4free
Mail List: www.engineer4free.com/newsletter
Thanks for watching, I hope it helps!
I want you to know that I was pretty sure I was going to fail a quiz. I watched this video at the last moment and ran to class. Now that it is over think I got everything right. Thank you so much!
Glad I could help! Check out all the statics vids I did at engineer4free.com/statics if you haven't already!! ✌️
Glad I could help! Check out all the statics vids I did at engineer4free.com/statics if you haven't already!! ✌️
great work bro
helped me a lot
I wish you would go through how you calculate the moments for x y and z directions because that is the most difficult part
The general method is described in the last half of this video, and the two following videos in the playlist use this method and go through the calculation of moments about the x, y, and z axis. Links are here: th-cam.com/video/sEJmLnrnY28/w-d-xo.html and here: th-cam.com/video/7zist6Y6N8g/w-d-xo.html
Engineer4Free could you do some videos on dynamic general plane motion of rigid bodies, and do a couple of examples of these sort of topics as I am finding them hard.
That's actually very helpful thanks a lot
Awesome, thanks for letting me know!
very clear and easy
Glad to hear it =)
How do you calculate the moment about a point that is not at A or the origin? Do you consider the moment(s) caused due to the reaction forces at A?
Yes you would have to also consider the moments cause by the reaction forces at A in the situation that you described. It would be possible to do with the same formula M = r X F where F is each reaction force and r is the position vector with tail at the point in question and head at the reaction in each case, lets call it rq in the next step. The expression for some arbitrary point "q" for this same example with the three applied point loads would be ΣMq = May + Maz + Max + r1XF1 + r2XF2 + r3XF3+ rqXFx + rqXFy + rqXFz = 0. The reason the last 3 terms don't show up in the expression for the sum of moments about A in the video is because their lines of action all pass through A, which means they do not cause a moment about A. In order to find the moment about another point q, you would need to know the fist 6 terms in the equation which you get by solving for the reaction at A anyways. I think you might be overthinking it if you are in a statics course right now. Statics problem should always just be focusing on trying to find the unknown reactions of statically determinate structures like in this video. The reason someone might want to find the net moment about some point that is not a reaction would be to determine the internal forces/moments/stresses at that location, but typically the reasons for wanting that information have to do with some topics in the field of mechanics of materials or structural analysis/design. So again, yes you are correct in your thought to also include the moments caused by the reaction forces, but I just think there's a pretty good chance that you don't need to be going down that road just yet if you're studying statics. I hope that clears it up and doesn't confuse you more haha :)
God thx for this channel. Thx.
thank u soo much
You're welcome!
THANKS
You're welcome!!
How can you determine the moment by using inspection approach, please help me
It's often to eyeball moments in 3D problems. 2D problems are much easier. I recommend checking out the "Moments" and "Three-Dimensional Static Equilibrium" sections here: engineer4free.com/statics
@@Engineer4Free thanks am going on to watch your lecture
Absolute Legend.
Thanks Jacqueline!! 🙌🙌
sir i want to ask.
why is torque: M = r x F?
what if i did : M = F x r ?
as i tried before, it gave negative result. does it matter at the final result?
Yes an (incorrect )negative answer is to be expected if you put the order backwards. You just need to remember to put the order correctly. Please see videos 9 - 12 here: engineer4free.com/statics for statics tutorials about the vector cross product
@@Engineer4Free thank you. i will watch ASAP. but please for quick question: everytime i do 2D statics problem, i never use vector. so yea i always do M = F times r (yes, scalar) . i forgot that it is actually r cross F. turns out i got negative value. will i still positive value at the final result? i mean, all of these equations equal to zero. so i think it doesn't matter if i start it with negative value, as long as i consistently (wrongly) do F x r? will it result in the same value as the correct r x F?
hey im a sophmore , should i try for an engineering career in college or something else? what is your opinions?
i'm also interested in computer science stuff. i used to want to be a surgeon but i heard it's hard
Those are existential questions that I can't answer for you. I'll keep my explanations limited to solving 3D statics problems 🙃
So helpedful, but I'm finding hard how to get a moment
🙌🏻🌹👏🏻…
please tell me something easier than this method....
Ahh sorry I only have videos on how to solve this way, once you get the hang of it I think it's the easiest / fastest way to solve 3D statics problems. Check out videos 38-41 here engineer4free.com/statics the more practice the easier it gets!