Hi, your videos are incredibly helpful! I do have to say that if you are in fact calculating the magnitude and location of the net resultant force on the bottom of the pool, then your y_c would be 3m, not the 1.5m( y_c is the distance from the liquid surface to the centroid of the area, which in this case if your area of concern is the bottom of the pool would be the full 3m depth to that centroid). 1.5 m would be used if you were calculating the force on the wall, in which case the area would be the 3m x 15m length of the pool.
The width is 5 and the length is 15, drawing is labeled incorrect. Also the force is a triangle and location is 2\3 from the surface is faster. Unless it’s a incline.
I have a question: Why is it 3x5 and not 3x15? I was just curious because aren't we trying to find the pressure and net force in the plain that goes into the page, which is the 15-meter dimension? whereas 3 meters is the plane parallel to the page.
Wow thank you so much for making these videos clearly and time sensitive to the exam I have a link to share you with a problem I’m struggling with because of how he obtained the centroid in the problem I’ll note the time in the video to not waste your precious time again thank you!
Shortcut for vertical submerged surfaces: Since force increases linearly with depth , you can draw a triangle, (0 pressure at the surface, mgh at bottom). Find the area (0.5*9.81*3). This will give you the average force which is what's applied at ycp. To get total force, multiply it by 15(length of pool). Since the force is in the shape of a triangle then where the average force is applied is 1/3 up from the bottom of the triangle (the y component of the centroid, 3/3=1ft).
You are right except by the fact that if you multiply the area (0.5*9.81*3) in [kN/m2] by the length of the pool 15 [meters] you are still left with a value in [kN/m] which is not a force. It is force per unit length. You will have to multiply the area again by 3 [meters] which is 662.2 [kN]. This is why I believe this problem is worded incorrectly. It does not tell you which face of the pool you need to calculate the resultant force on. She is really solving for the net force on the front wall of the pool with area 3*5 [m2] (as if the force points out of the page) not on the side wall (or right wall) which iis 3*15 [m2].
quick hint Ycp is just 2/3 of the height of the gate since we know the pressure triangle has a force that acts 2/3 from the top of the surface (2/3)*3= 2 m
Hi, please clarify to your viewers that you are really solving for the net force acting on the front wall of the pool with area 3*5 = 15 [m2], not the side wall. If you use the side wall, you get a net force of 662.2 kN instead of 221 kN.
girll!! thanks so much for the problems. My teacher for fluids is making out tests all FE format. Where can I find the resources to fluid mechanics problems? Right now, the problems would be from fluid properties (surface tension) to fluid statics(hydrostatic eq., pressure on panels), designing a dam, etc. Ch.1 -Ch.3 on the fluid mechanics book :) Thank you~
Thank you for watching and for being here. For the books, you can get the FE practice problem by Linderburg. In the description, under this video, I shared links to the books that I used to study for my FE exam. Also, I think my favorite book is Study Guide Fundamentals of Fluid Mechanics, check link in the description, but this book provides so many examples with the solutions. It also helped me a lot when I was taking Fluid Mechanics class. Good luck with your classes and please share my videos with your engineering friends 😊
Hey I have a doubt about this problem. Since the swimming pool is embedded in soil or there is soil around on all three sides. Can we still sue the Patm on both side equation or should we use the Fr on wetted side equation?
If you take the moment, the moment of the resultant force must equal the moment of the distributed pressure force, therefore, the resultant force would not act at the centroid. I hope this makes sense and good luck with your studying!
Quick question. Was the figure given by the problem? or did you create the drawing before we started to solve the problem? If the figure was not given, then how could we know if we use the 5m wide base or the 15m long base for the moment of inertia calculation?
The figure is provided. Also, when calculating for the area and the moment of inertia, always use the width. Usually, the width is specified. I hope this helps and good luck 😊
It is confusing because the first problem you go over in the playlist is similar with a 4x4 gate (going into the paper) where as this one I would think would be 3x12.
i took an updated FE civil practice test. and it talks about a block on an inclined plane, a thin film of oil in between, velocity, temperature of oil and absolute viscosity. you have any sample problems like that?
Thanks . could please check the moment of inertia. I think should be bh^3/12 so 15* 3^3/ 12= 33.75 and check area. or you can make clear of the question say magnitude force on wide side or long side.
Hello Azim, in the question, it shows that the base or the width of the pool is 5 m, that is why we are using 5 instead of 15. Also, 15 m is the length of the pool, which is going into the page, and usually the length is not used in these type of problems. I hope this helps and good luck with your studying!
When calculating for Fr,net, why did you use 3x5 as the area and not the 15x15? In the other video for forces acting on an inclined plane, you use the 4x4 as the area when calculating for Fr,net.
So in the previous problem, we were given a 4x4 square, in this problem, we have a rectangle, so the area would be width time depth, and we ignore the length. I hope this makes sense.
enGENIEer thank you for this useful explanation, but why the area is not 3m x 15m?, I know you said we should ignore the length (15), but isn’t the effective area 3m x 15m?
@@gh5030 So if you try to imagine the length of this pool, it would be going into the screen, but the area in this equation refers to the area of the bottom of the pool, so the only two dimensions that we consider are the width and depth. I hope this makes sense and good luck with your studying!
@@Genieprep Hi @Genieprep You said "the area of the bottom of the pool", but you say to just consider "the width and depth". Unfortunately, that doesn't make sense. The area of the bottom of the pool would be the length and the width.
The question is confusing because it didn't say which face the pool the question needs the force acting on to be calculated since there is 4 faces for the swimming pool. Also, if the figure associated with the problem then it makes it more confusing since the section shows the 3x15 vertical surface on the right. Now, the only option we have left with is the trail and error to match the right answer from the multiple answer provided. Thanks
Your videos are very helpful for FE exam takers ...my question will be how do you calculate tan^2(29°).....I just would not get it right on my calculator..HELP PLEASE...thank you
Hello, so Yc is the centroid of the pool, but it is not the same thing as Ycp, which is the center of pressure. The resultant force acts at the center of pressure and not at the centroid. I hope this makes sense and good luck.
Yes that’s very precise. Just wanted to confirm one more thing that for centroid yc are we referring to the FE manual page-74 figure #4 would you please comment so that the concept is airtight !!
ua-cam.com/video/2ssodW8tVSA/v-deo.html At 47:33 in the video is where he started to demonstrate the problem and how he got his centroid and area in the problem is a little confusing if you made a video clearing that up I feel like everyone’s understanding would help them in the exam again thank you
Hahaha 😂 don't say that! I am here to help! Send me an email at engenieeronline@gmail.com and I will send you some practice problems and some tips on how to study for this test! It is really not that bad of a test! Good luck with your studying and STAY POSITIVE 😊😂! Talk to you soon!
Why is the area 3x5 and not 3*15
Hi, your videos are incredibly helpful! I do have to say that if you are in fact calculating the magnitude and location of the net resultant force on the bottom of the pool, then your y_c would be 3m, not the 1.5m( y_c is the distance from the liquid surface to the centroid of the area, which in this case if your area of concern is the bottom of the pool would be the full 3m depth to that centroid). 1.5 m would be used if you were calculating the force on the wall, in which case the area would be the 3m x 15m length of the pool.
The width is 5 and the length is 15, drawing is labeled incorrect. Also the force is a triangle and location is 2\3 from the surface is faster. Unless it’s a incline.
I have a question: Why is it 3x5 and not 3x15? I was just curious because aren't we trying to find the pressure and net force in the plain that goes into the page, which is the 15-meter dimension? whereas 3 meters is the plane parallel to the page.
Ditto
Wow thank you so much for making these videos clearly and time sensitive to the exam I have a link to share you with a problem I’m struggling with because of how he obtained the centroid in the problem I’ll note the time in the video to not waste your precious time again thank you!
Shortcut for vertical submerged surfaces:
Since force increases linearly with depth , you can draw a triangle, (0 pressure at the surface, mgh at bottom). Find the area (0.5*9.81*3). This will give you the average force which is what's applied at ycp. To get total force, multiply it by 15(length of pool). Since the force is in the shape of a triangle then where the average force is applied is 1/3 up from the bottom of the triangle (the y component of the centroid, 3/3=1ft).
You are right except by the fact that if you multiply the area (0.5*9.81*3) in [kN/m2] by the length of the pool 15 [meters] you are still left with a value in [kN/m] which is not a force. It is force per unit length. You will have to multiply the area again by 3 [meters] which is 662.2 [kN]. This is why I believe this problem is worded incorrectly. It does not tell you which face of the pool you need to calculate the resultant force on. She is really solving for the net force on the front wall of the pool with area 3*5 [m2] (as if the force points out of the page) not on the side wall (or right wall) which iis 3*15 [m2].
quick hint Ycp is just 2/3 of the height of the gate since we know the pressure triangle has a force that acts 2/3 from the top of the surface (2/3)*3= 2 m
Hi, please clarify to your viewers that you are really solving for the net force acting on the front wall of the pool with area 3*5 = 15 [m2], not the side wall. If you use the side wall, you get a net force of 662.2 kN instead of 221 kN.
girll!! thanks so much for the problems. My teacher for fluids is making out tests all FE format. Where can I find the resources to fluid mechanics problems? Right now, the problems would be from fluid properties (surface tension) to fluid statics(hydrostatic eq., pressure on panels), designing a dam, etc.
Ch.1 -Ch.3 on the fluid mechanics book :)
Thank you~
Thank you for watching and for being here. For the books, you can get the FE practice problem by Linderburg. In the description, under this video, I shared links to the books that I used to study for my FE exam. Also, I think my favorite book is Study Guide Fundamentals of Fluid Mechanics, check link in the description, but this book provides so many examples with the solutions. It also helped me a lot when I was taking Fluid Mechanics class. Good luck with your classes and please share my videos with your engineering friends 😊
Hi Kenza, what version of FE reference Handbook are you using for this video please? your page is different with my FE book pages, thanks.
Hey I have a doubt about this problem. Since the swimming pool is embedded in soil or there is soil around on all three sides. Can we still sue the Patm on both side equation or should we use the Fr on wetted side equation?
Shouldn't the problem specify which surface area are we interested in?
Thank you. It has been a while.
Thank you for this video! Can you remind me why the resultant force cannot take place at the centroid?
If you take the moment, the moment of the resultant force must equal the moment of the distributed pressure force, therefore, the resultant force would not act at the centroid. I hope this makes sense and good luck with your studying!
Quick question. Was the figure given by the problem? or did you create the drawing before we started to solve the problem? If the figure was not given, then how could we know if we use the 5m wide base or the 15m long base for the moment of inertia calculation?
The figure is provided. Also, when calculating for the area and the moment of inertia, always use the width. Usually, the width is specified. I hope this helps and good luck 😊
It is confusing because the first problem you go over in the playlist is similar with a 4x4 gate (going into the paper) where as this one I would think would be 3x12.
Drew Nezelek it should be the depthx length of the wall
Can you please make a video for thé chèche sheet for each topic
Ex: math
Fluid
Thermo
Statics
Dynamic...etc!
i took an updated FE civil practice test. and it talks about a block on an inclined plane, a thin film of oil in between, velocity, temperature of oil and absolute viscosity. you have any sample problems like that?
Thanks . could please check the moment of inertia. I think should be bh^3/12 so 15* 3^3/ 12= 33.75 and check area. or you can make clear of the question say magnitude force on wide side or long side.
Hello Azim, in the question, it shows that the base or the width of the pool is 5 m, that is why we are using 5 instead of 15. Also, 15 m is the length of the pool, which is going into the page, and usually the length is not used in these type of problems. I hope this helps and good luck with your studying!
Why doesn't this formula work if you have 2 different structure sections (upright and slanted) ? Can you please do an example on this.
b = 5 m has no effect
When calculating for Fr,net, why did you use 3x5 as the area and not the 15x15? In the other video for forces acting on an inclined plane, you use the 4x4 as the area when calculating for Fr,net.
So in the previous problem, we were given a 4x4 square, in this problem, we have a rectangle, so the area would be width time depth, and we ignore the length. I hope this makes sense.
enGENIEer thank you for this useful explanation, but why the area is not 3m x 15m?, I know you said we should ignore the length (15), but isn’t the effective area 3m x 15m?
@@gh5030 So if you try to imagine the length of this pool, it would be going into the screen, but the area in this equation refers to the area of the bottom of the pool, so the only two dimensions that we consider are the width and depth. I hope this makes sense and good luck with your studying!
@@Genieprep Hi @Genieprep You said "the area of the bottom of the pool", but you say to just consider "the width and depth". Unfortunately, that doesn't make sense. The area of the bottom of the pool would be the length and the width.
The question is confusing because it didn't say which face the pool the question needs the force acting on to be calculated since there is 4 faces for the swimming pool. Also, if the figure associated with the problem then it makes it more confusing since the section shows the 3x15 vertical surface on the right. Now, the only option we have left with is the trail and error to match the right answer from the multiple answer provided. Thanks
Exactly, this question is not clear at all!
Thanks for the good video
Thank you
Hi is the moment of inertia formula given in handbook
Hello Surya, the equation is on the reference handbook, page 73 under statics section. Thank you for watching!
@@Genieprep this is sooper quick response. Thanks much :)
Your videos are very helpful for FE exam takers ...my question will be how do you calculate tan^2(29°).....I just would not get it right on my calculator..HELP PLEASE...thank you
Hi,
Thanks for sharing this concept. Can you please explain the rule of determining yc =1.5 m. Thanks very much!
Hello, so Yc is the centroid of the pool, but it is not the same thing as Ycp, which is the center of pressure. The resultant force acts at the center of pressure and not at the centroid. I hope this makes sense and good luck.
Yes that’s very precise. Just wanted to confirm one more thing that for centroid yc are we referring to the FE manual page-74 figure #4 would you please comment so that the concept is airtight !!
Yes that is correct.
enGENIEer thanks very much !!
I have doubt in this problem resultant and area
Your skin is flawless.
Hi Kenza :D !
very strange approach. why do you need to apply slanted plane formula?
Definitely Smash
ua-cam.com/video/2ssodW8tVSA/v-deo.html
At 47:33 in the video is where he started to demonstrate the problem and how he got his centroid and area in the problem is a little confusing if you made a video clearing that up I feel like everyone’s understanding would help them in the exam again thank you
Hello John, I will take a look at it and I will see what I can do. Thank you for reaching out and good luck with your studying.
Thank you!!
I’m from ASI can you guess who I am ?
god I am going to fail so hard on the fluid mechanics questions
Hahaha 😂 don't say that! I am here to help! Send me an email at engenieeronline@gmail.com and I will send you some practice problems and some tips on how to study for this test! It is really not that bad of a test! Good luck with your studying and STAY POSITIVE 😊😂! Talk to you soon!
This is long process. It can be solved very quickly.
You made a mistake here, the width in the drawing is 15 m wide.
Hi, the length is 15m. The width is 5m.