Centre of pressure report PDF

Title Centre of pressure report
Author LuN-cHaY 98
Course Civil Engineering
Institution Universiti Teknologi MARA
Pages 7
File Size 349.2 KB
File Type PDF
Total Downloads 253
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Summary

HYDRAULIC LABORATORYECWOPEN-ENDED LABSEPT 2018 – JAN 2019TITLE OF EXPERIMENT : Center of Pressure DATE OF EXPERIMENT : 13th March 2020 GROUP : 3B GROUP MEMBERS 1. SITI NURIZZATI BT NORDIN- 2. AHMADKAMIL HAKIM BIN GHAZALLI 2017800438 3. MUHAMAD NAZMI SHAHIR BIN MOHD NOR 2017800308 4. MUHAMMAD SYAUQI ...


Description

HYDRAULIC LABORATORY ECW437 OPEN-ENDED LAB SEPT 2018 – JAN 2019 TITLE OF EXPERIMENT

: Center of Pressure

DATE OF EXPERIMENT

: 13th March 2020

GROUP

: 3B1

GROUP MEMBERS

1. SITI NURIZZATI BT NORDIN-2018683488 2. AHMADKAMIL HAKIM BIN GHAZALLI 2017800438 3. MUHAMAD NAZMI SHAHIR BIN MOHD NOR 2017800308 4. MUHAMMAD SYAUQI BIN IZAHAM 2018276386 5. Zarish Hafilda Binti azlan 2018239008

LECTURER

:

LEVEL OF OPENESS

:

0

MARKS

COMMENTS

INTRODUCTION BASIC CONCEPTS METHODOLOGY RESULTS DISCUSSION

1

2

3

4

5

CONCLUSION

1

2

3

4

5

ORGANIZATION

1

2

3

4

5

TOTAL MARKS

INTRODUCTION The need for an open-ended laboratory activity is emphasized in enhancing independent learning activities and inculcating creativity and innovation of students. It is now a required element in an accreditation exercise as stipulated in the EAC Manual 2012. Hydrostatic pressure is the pressure that exerted by fluid at rest due to the weight of fluid above the surface. Hydrostatic Pressure System allow for the measurement and development of hydrostatic force and center of pressure equations. To demonstrate this capability, the loads were added to one end of and Edibon Hydrostatic Pressure System, and water was added into the system until the arm was level (balancing the moment about the pivot).

OBJECTIVES To determine the position of the center of pressure on the rectangular face of the torroid.

Problem Statement We are required to conduct an experiment on the Centre of Pressure Apparatus to determine the centre of pressure on a vertical rectangular plane surface. We are required to investigate the percentage of errors between the experimental depth, hpe and the theoretical depth, hpt of the centre of pressure for fully submerged and partially submerged and partially submerged vertical rectangular face of the torroid. All readings and data from the experiment should be tabulated accordingly. The factors that contribute to the differences between hpe and hpt for fully submerged and partially submerged has been discussed. Theoretical Background The centre of pressure may be defined as: “The point in the plane at which the total liquid thrust can be said to be acting normal to the plane”.

Where: b = Width of the vertical rectangular face of the torroid (m) d = Depth of the vertical rectangular face of the torroid (m) L = Length measured from the pivot to the load hanger (m) hg = Depth from the free water surface to the centre of pressure (cp) of the vertical rectangular of the torroid submerged in water (m). y = Depth from the pivot to the centre of pressure (cp) (m) y1 = Depth measured from the pivot to the free water surface (m) y2 = Depth measured from the free water surface pivot to the base of the torroid (m) y1+y2 = 0.200 m (20cm) F = Hydrostatic thrust on the vertical rectangular face of the torroid (N) W = Weight recorded on the load hanger (N) The experimental location of the centre of pressure (cp) on the vertical rectangular face of the torroid from the pivot can be determined by taking moments about the pivot: F x y =W x L

y=

WL (i) F

The forces on the vertical rectangular face of the torroid is given by: F=γh g A=ρghgA (ii ) Where

γ

= Specific weight of water (N/m3)

ρ = Mass density of water (kg/m3) g = Acceleration due to earth’s gravity (m/s2) A = Area of vertical rectangular face of torroid (m2) d hg= y 2− (iii) 2 The experimental depth of the centre of pressure can be derived from: hpe h pe= y − y 1(iv) The theoretical depth of the centre of pressure can be derived by the equation below: hpt =hg +

Ig (v) Ahg

Where Ig = second moment of area about an axis through the centroid of the vertical rectangular face of torroid (m4) = bd3/12

Procedures 1. The width (b) and depth (d) of the rectangular face of toroid were measured. 2. The length, L from the pivot to the load hanger was also measured. 3. The three (3) foot screws were adjusted until the apparatus is balanced. This will be indicated by the spirit level situated at the left base of the apparatus. 4. The balance arm was adjusted until it is level by using the rider. 5. The tank was filled with water using the measuring cylinder to the zero scale datum (just touch the base of the vertical rectangular face of toroid and can be adjusted by opening or closing the outlet valve situated at the bottom of the tank). 6. The tank was filled with water again to a certain level about 1 cm from the top of the tank. 7. The weights were placed on the load hanger to restore the balance arm to the horizontal position. 8. The weights, W on the load hanger were recorded and y2 was measured. 9. It was repeated for at least nine (9) other values of weights, W and depths, y2.

Results and Analysis Area = 0.1 m * 0.075 m = 0.0075 m L = 0.277 m y1 + y2 = 0.2 m

Weight, W (N)

Depth, y2 (m)

Depth, y1 (m)

0.5

0.047

0.153

1.0

0.066

0.134

1.5

0.082

0.118

2.0

0.096

0.104

2.5

0.109

0.091

3.0

0.122

0.078

3.5

0.129

0.071

4.0

0.146

0.054

4.5

0.159

0.041

5.0

0.175

0.025

y2(m

y1(m

W(N

)

)

)

hg(m)

A(

F(N)

y(m)

Ig

m2

Hpe(m

Hpt(m

)

)

0.045

0.059

-0.002

0.045

0.009

0.055

0.025

0.067

0.041

0.078

0.056

0.090

0.073

0.097

0.085

0.113

0.098

0.125

0.112

0.141

) 0.047

0.153

0.5

0.009

0.0075 0.699

5

0.19 8

3.516 × 10−6

0.066

0.134

1.0

0.028

0.0075 2.096

5

0.13 2

3.516 × 10−6

0.082

0.118

1.5

0.044

0.0075 3.274

5

0.12 7

3.516 × 10−6

0.096

0.104

2.0

0.058

0.0075 4.304

5

0.12 9

3.516 × 10−6

0.109

0.091

2.5

0.071

0.0075 5.261

5

0.13 2

3.516 × 10−6

0.122

0.078

3.0

0.084

0.0075 6.217

5

0.13 4

3.516 × 10−6

0.129

0.071

3.5

0.091

0.0075 6.732

5

0.14 4

3.516 × −6

10 0.146

0.054

4.0

0.108

0.0075 7.983

5

0.13 9

3.516 × 10−6

0.159

0.041

4.5

0.121 5

0.0075 8.939

0.13 9

3.516 × 10−6

0.175

0.025

5.0

0.137 5

0.0075 10.117 0.13 7

3.516 × 10−6

Discussion From the experiment we can see that there are difference value in hp of experiment and hp of theoretical. This may occur due to human error in reading of balance bridge arm level. This would lead to an inaccurate water height reading, which would consequently affect everything height was used to calculate other than that, there might be human error in reading the height of the water in the chamber. This also would cause the height measurement and all subsequent calculations. Next, the error during splashing the water into the balance bridge arm might occur too. When we poured the water and of course this would cause an artificial increase in weight due to the applied masses. The applied masses were not weight prior to their application onto the balance bridge arm. Thus, the applied mass may weight more due to accumulation of oils from being handled. However, all those errors that might be occurred are so minor that is likely that even if they were present in the experiment, they would have little to no effect on the result.

Conclusion We have conducted an experiment of centre of pressure. We found that there is an error when calculating the experimental depth from the water surface to the centre of pressure due to the incorrect reading of the depth by using a ruler. Based on the objective of this experiment, we are able to determine the position of the centre of pressure of the rectangular face of the torroid based on data that we achieved. We find that the centre of pressure is always below the centre of gravity because the pressure is higher at deeper points on vertical surface. Therefore, the position of centre of pressure is not same as centre of gravity in a vertical surface Reference 1. https://www.tecquipment.com/centre-of-pressure 2. https://www.scribd.com/doc/305411308/Hydrostatic-force-Centre-of-Pressure-LabReport 3. http://www.sfu.ca/~mbahrami/ENSC%20283/Lab/Center%20of%20Pressure%20and %20Hydrostatic%20Force%20on%20a%20submerged%20body-Rev.pdf...


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