Lab 3: Measurement of Hydrostatic force on an immersed plane and locating the center of pressure

In this webcast, we show how to determine the hydrostatic force on a partially/fully submerged surface and locate the center of pressure. We show the theory, working principle, test procedure, and data collection with a demonstration. You need to watch the theory and demo before Intro to Fluid Mechanics lab class to be prepared ready performing the lab on your own. #Hydrostatic_force #Fluid_Mechanics #Center_of_pressure

[@sandisosenzo]

I liked the part where you said the force on the sides of the quadrant balance one another and that the force on the curved surface creates no moment hence we focus on the force at the quadrant vertical face. Thanks a lot for this

[@MohammadShafinulHaque]

You're welcome 😀

[@deejunyikm-pelajar9724]

sir explained so clearly for every step of the experiment, thanks a lot!!

[@MohammadShafinulHaque]

You are welcome.

[@laoluafuye322]

I have 3 questions about this experiment 1. How and why does the thrust vary with depth? 2. What happens when the plane becomes fully submerged and why? 3. why might there be discrepancies between the experimental and theoretical results for the thrust?

[@azizazaini1700]

Thank you sir! Have a great day!

[@MohammadShafinulHaque]

You're welcome.

[@Alyrwani99]

This so helpful, Thank you very much sir

[@MohammadShafinulHaque]

You're welcome

[@saimsiddiqui1544]

Very good sir .. Can you explain when this experiment was done on fully submerged and partially submerged surfaces? I couldn't get the concept of partially and fully submerged in experimental point of veiw

[@MohammadShafinulHaque]

Hi Sami, Look at 6.40 min where the horizontal line represents the water level and the vertical surface is partially submerged. At 8.36 min the verticle surface is fully submerged leading to different COP location. Similarly, around 15.10 min you will see the example of partially submerged, and around 18.09 min you will see a fully submerged scenario.

[@saimsiddiqui1544]

@@MohammadShafinulHaque thanks sir

[@MohammadShafinulHaque]

@@saimsiddiqui1544 you're welcome.

[@justinmccarthy6491]

Doesn't the submerged portion of the quadrant contribute a buoyancy force? Would that effect the moment in addition to the hydrostatic force?

[@MohammadShafinulHaque]

Very good question Justin. The buoyancy force is part of the hydrostatic force. The knife-edge pivot coincides with the center of the arc of the quadrant. Any forces on the curved surface pass through the pivot and have no effect on the moment. Forces on both sides are equal and cancel out. Only the force on the rectangular plane contributes to the moment.

[@abdullahbinsajjad4070]

Very good explanation

[@MohammadShafinulHaque]

Thank you Abdullah

[@inaamalawwad]

What is the difference if we added water first or the weight first?

[@MohammadShafinulHaque]

There is different cases that we test, such as partially submerged or fully submerged. If you pour the water first and don't know how much water you need, you may need to take out water. Make sure you don't have any spill water on the top of the body, that's an added weight.

[@minenhleshabane5472]

Sir would like to know when filling the table, how you calculate the exper.. and theo moment I couldn't understand on the video ,, is there a different ?

[@MohammadShafinulHaque]

The experimental moment will come from experimental COP (h) and the theoretical moment will come from theoretical COP(h), notice @7.26 minute and 8.26 minute the experimental (h) depends on mass and the theoretical depends on dimensions, and they will be close value but different, thus the moment will be different.

[@minenhleshabane5472]

@@MohammadShafinulHaque Thank you very much

[@MohammadShafinulHaque]

@@minenhleshabane5472 you are welcome.

[@AlexRodriguez-so4bs]

is there a way you could show the derivation for the theoretical Fr?

[@vanshdesai5730]

what is the density of the quadrant?

[@hariz2254]

nice video i like

[@MohammadShafinulHaque]

thank you

[@saraalma2085]

I really need the answers for the questions, I dont know which formula I should use for each question:(

[@MohammadShafinulHaque]

What questions?

[@momamun9557]

Hello sir I have a questions What happens when the plane becomes fully submerged compared to partially submerged and why ?

[@MohammadShafinulHaque]

The hydrostatic force acting on the vertical face changes. Since the partially submerge has force on only the partially submerged surface. See the force equation at min 7:40 and min 8:40 of the video.

[@waqarkhanyousafzaii7464]

in fully submerged part of this video experimental formula for finding hR' why it is written mL not mgL plz explain sir where is the gravity force

[@MohammadShafinulHaque]

Waqar, thank you for your question. Look at video time 8.31 min. Here h = mgL/F, plug the value of force F in the equation and replace the Sp. weight (gamma) = density (rho) * gravitational ACC. (g). Then "g" will cancel out. Hope this helps. :)

[@moonlight-vx4ti]

Can you answer my questions? Is there a difference between the value of theoretical and laboratory force? Why?

[@MohammadShafinulHaque]

A difference between the theoretical and laboratory force may exist as there is a difference between theoretical and experimental (h). If you observe the force equation it depends on the specific weight and depth of immersion (d), while B (for partially submerged) and B&D (for fully submerged) are fixed. Differences may arise due to human error in reading water temperature, and reading (d), something temperature of the water may change all these can lead to different values.

[@moonlight-vx4ti]

@@MohammadShafinulHaque Thank you sir, but I have 3 questions besides this question 1- Is the force by weight the same as the experimental force? Why? 2- Any force of water pressure greater, in case of partial immersion or total immersion? Why? 3- What is the relationship between mass and the water depth? Why?

[@moonlight-vx4ti]

@@MohammadShafinulHaque Can you answer my questions briefly?

[@MohammadShafinulHaque]

@@moonlight-vx4ti (1) the force by weight is not the same as hydrostatic force (F), as they are related by mgL=Fh, thus mg is not equal to F generally. (2) I am not clear what you are asking in this question, can you clarify your question? Are you asking which force is greater? partial or fully immersed? (3) See the force equation at times 7.40 and 8.40, F increase with depth of immersion d.

[@moonlight-vx4ti]

@@MohammadShafinulHaque Thank you very muchsir،You helped me a lot. Regarding question 2, yes like this

[@abdallahhachimi6579]

Why didn't u calculate Lcg&Lcp

[@ZULFERISYAHPUTRA]

Dear Sir............Example Problem I have a single acting hydraulic cylinder with a stroke of 300 mm, a bore of 18 mm and a rod of 10 mm if the press weight is 1 mm on the Piston Head what is the pressure.....Please explain the calculations

[@MohammadShafinulHaque]

Refer to a fluid mechanics book

[@hirushagamage1366]

Thankyou sir

[@MohammadShafinulHaque]

You're welcome.

[@ryzenfurry413]

where's is your answer ang solving equations

[@MohammadShafinulHaque]

All equations needed for this lab are in the video, once you have the lab test data you should be able to solve.

[@e2000-r2l]

Thaaaaannnksssssss

[@MohammadShafinulHaque]

You are welcome Erfan.