Those days when you feel like your job as a dad is paying off. I have just found this video on my 13 years old daughter watching list while she was using my account, along with other videos on your channel and not a single video on makeup or clothes, but just videos on engineering and animal welfare and protection. I am so proud of her right now, i had to leave a comment. I am going to send her to the university of her choice regardless of the tuition even if i have to sell a kidney.
I think this is a practical and better observation of discussing higher maths like college physics, and engineering mechanics. I quite struggled from the textbooks and with the teachers who always stick with their writings and drawings in the board.
7:00 there's definitely an error here. You can see that the two lower indicators are showing both 21 N, but the pointers are in different places. That makes sense, since the lower pressure should be higher than the higher one
7:00 Not sure, but for the water one, is the Pv lower than the Ph because some of the water weight is supported by hanging. So if there's no hanging, the Ph will be the same as Pv (2.5 kPA). Or in other word, the top support 0.4 kPA. Not very sure so correct me if I'm wrong.
The possibility of K>1 was alluded to in the video (and indeed ever so briefly shown as you point out) but not explained. It's counter intuitive to me and I'd like to hear how that can come about.
What do you mean by hanging? If there is a reduced vertical pressure (by whatever means even if it's just an imagined or intuitive scenario) there is always a corresponding reduced horizontal pressure. Because the horizontal pressure comes only from a gravity. (In a static situation). Yes, a formula can always express an imagined or theoretical outcome if some of the factors are altered from theory. You could think of this as being why mathematics is considered a theoretical subject. These formulas just "represent" the physical.
In reference to the diagram at 7:00, extrapolating out the figures to represent that horizontal line is nonsense. The line should have referenced the lowest edge of each plate not the centre point of the piston.
Wait. How did that water example (7:02 in the video) end up with a K above 1? I get that there is an averaging effect of the bottom-most horizontal force measurement because the plexiglass sidewall spans several cm of height. But if the bottom lateral force is indeed 2.5... why does the vertical force display 2.1 instead of 2.5 meaning that the resulting K is 1.0? How it is physically possible for K to exceed 1.0?
Question from non engineer type. If an IBC tote can hold 330 gallons of liquid and liquid has pressure force in all directions, would it also be able to hold an equal volume of gravel, stone or sand, since this material would have less side pressure and more downward force? Reason. I've thought about using recycled IBC totes (come on plastic pallet with metal ribs) as a buttress instead of a gabion structure for retaining wall. I understand the back fill needs to have a correct structure to keep hydraulic forces under control. Very informative videos. Thanks, Scott
yes this is correct. But logical error mostly. At the same level of water, without the shape of the container difference pressure will always be same. So not 2.2 and 2.5 kpa. Its always the same.
This is an experiment and it will never produce values exactly as you expect. There is always a margin of error. From where the error arises? Lack of precision of the equipament is likely, as is the approximation that generated that graph, but I would say it is likely due to the air around the bag that contains the water along with the bag itself.
@@Expllosaoriginal I agree. Experimental values will not reproduce theory exactly. But his values are way off. Kp cannot be bigger then 1 (in a perfect experiment). Yet he calculates a value of 1.2 In this case he should have either * figure out why his measurements are that much in error with respect to the theory * not show the experiment at all (since it is pretty clear that something disturbs the experiment) * "adjust" the numerical values "a little bit". In any case: Showing a value of 1.2 (with a maximum of 1) is the worst thing you can do. A 20% error makes all other experiments shown quantitatively questionable. (And like you I am pretty sure that there is some problem with the setup. Also one might consider a wrong read from the instruments or forgetting to reset them to exactly 0. There are a number of reasons why such a thing can happen. I am fine with that in a live presentation. But if you prepare a video, things like that should never go unnoticed)
I've gone through all your videos and they're very interesting but I haven't been able to find what I'm looking for. I'm building a raised garden bed 12'x4' and 3' tall. I'm going to reinforce the inside of the walls to prevent the walls from bowing and I'd like to know how much pressure the soil will generate. Do you know a formula I can use?
you cant as they are linked. in practice you know the K value from books/ tables so you can calculate the horizontal pressure. for soil on the other hand the value K is calculated from fi
So I have a question then, when backfilling a retaining wall which produces more thrust? Granular material or compacted clay(sticky)? I believe granular would produce more thrust simply because it will not hold a vertical face where compacted clay will.
Cameron Turner Clay is a funny one. What appears solid can actually be liquid but slow moving. The "stickiness" was described in the flat M&Ms model but that's a different kind of sticky. (High static friction v friction in motion.) When the surfaces are "sticky" with high static friction the K figure drops, But clay can still be moving. Any sticky material's K constant can almost drop to zero..... until you have seismic vibration. When that happens the clay will alter consistency and has the potential to act like anything on the scale from solid to liquid. With retaining walls it's wise to treat every point load as having to hold back water.
I guess measurement in real life does not also get the theoretical values due to systematic errors in the setup. But I wonder if the Engineering Models can explain the discrepancy in the engineering point of view.
pressure is a per area quantity. Measuring both sides = double the force, but also double the area. So pressure = force/area is the same as measuring from one side.
These are well done. Let me say something because you should have more subscribers and way more views. The emphasis on equations is suppressing your popularity. It is possible to explain the concept without using any equations. Just explain the concept with layman's terms. When Stephen Hawking published his book, A brief history of Time, he says his publisher told him that for every equation he would put into the book, the readership would halve. So explained cosmology without any equations except the famous E = mc2 . IT went on to sell 10 million copies. I bought a copy from a thrift store and I had trouble understanding it even without the equations. Check out Practical Engineering. He does a good job of avoiding equations and he has about a million subscribers now doing what you're doing. That means people are interested in these topics. Just explain things in layman's terms and use models for visual aids.
@@Barnaclebeard You must be an engineer. Relax a little if you can, and understand that making education entertaining is a terrific way of growing the appeal of it. I know, can you imagine, if engineering became a popular choice for kids starting in Uni because it actually seemed like fun rather than the dour old pipe smoking smell it used to have? Thats what Engineering models has done here, and made it so much fun to engage with, that it inspired extra study into the work (well, it did at least for me). Can't beat that. Unless having undies so tight that your Adam's Apple makes you sing like Mariah Carey seems more attractive to you.
The video is made by Professor Wayne Brodland at the University of Waterloo, and I assume it is supposed to be supplementing an engineer's education, rather than trying to appeal to a wide audience. Practical Engineering's video's are good, but these videos are more useful to an engineering student, as they can see the equations directly relating to the topic. It's fine even if this channel doesn't get super popular, there always ought to be someone that gets into the nitty gritty details that nobody cares about. A Brief History of Time is a book that sold well for sure, but it's not particularly useful as a learning aid for someone actually trying to study cosmology and needs the equations.
