TOPIC 4 - Principle of Moments lab report

19 

Loading.... (view fulltext now)

Loading....

Loading....

Loading....

Loading....

Full text

(1)

UNIVERSITI TUN HUSSEIN ONN MALAYSIA

Faculty of Mechanical and Manufacturing Engineering

DEPARTMENT OF ENGINEERING MECHANICS

STATICS LABORATORY

LAPORAN MAKMAL/LABORATORY REPORT

Kod M/Pelajaran/

Subject Code LABORATORY IENGINEERING BDA 17001 Kod & Tajuk Ujikaji/

Code & Title of Experiment TOPIC 4: PRINCIPLE OF MOMENTS Kod Kursus/ Course Code BNJ17001 Seksyen /Section 6

Kumpulan/Group

7

No. K.P / I.C No.

Nama Pelajar/Name of

Student LUQMAN HAKIM B MOHD MASROR

No. Matrik Lecturer/Instructor/Tutor’

s Name

1.EN. MOHD NAZRUL BIN ROSLAN 2.

Nama Ahli Kumpulan/

Group Members No. Matrik Penilaian / Assesment

1. LUQMAN HAKIM B MOHD MASROR AN12011 5 Teori / Theory 10 % 2. FUAD RIDZUAN B MOKHTAR AN12011 3 Keputusan / Results 15 % 3. ARIF AIMRAN B AHMAD AN12012

9 Pemerhatian /Observation 20 % 4. NORASIKIN BT AB RANI AN120032 Pengiraan / Calculation 10 %

Perbincangan / Discussions 25 % Tarikh Ujikaji /

Date of Experiment 4 OCT 2012 Kesimpulan / Conclusion 15 % Tarikh Hantar /

Date of Submission 11 OCT 2012 Rujukan / References 5 % JUMLAH / TOTAL 100% ULASAN PEMERIKSA/COMMENTS COP DITERIMA/APPROVED STAMP

(2)

COURSE INFORMATION

COURSE TITLE: ENGINEERING LABORATORY I (BDA17001) TOPIC 4: PRINCIPLE OF MOMENTS

1. INTRODUCTION

The principle of moments is frequently used in engineering and building work where forces have to be balanced to prevent any turning movement. It can be applied both to parallel forces and to oblique forces. If a body has several forces applied to it which have turning effects in opposite directions, the body will not turn if the total turning moment in each direction are equal. This is called Principle of moments.

2. OBJECTIVES

The objective of this experiment is to verify the principle of moments for parallel and non-parallel forces.

3. LEARNING OUTCOMES

At the end of this topic, the students will be able to display basic skills and knowledge of principle of moments using laboratory equipments, analyze observable data obtained from principle of moments experiment properly, work effectively in a group through laboratory experiment and presentation and demonstrate comprehension of the general ideas of the topic through written report that comply with specified standards.

4. THEORY

A concept often used in mechanics is the principle of moments, which is sometimes referred to as a Varignon’s theorem since it was originally

(3)

d2 d1 F1 F2 F d F d

UNIVERSITI TUN HUSSEIN ONN MALAYSIA

Faculty of Mechanical and Manufacturing Engineering

developed by the French mathematician Varignon. The moment of a force indicates the tendency of a body to turn about an axis passing through a specific point.

It was defined as, M = F x d (in Nm) ……… (1) Which, F is the action of force;

d, is the perpendicular distance between F and centre of moment. (Figure 1a/1b)

The principle of moments states that the moment of a force about a point is equal to the sum of the moments of the forces components about the point. For a body in equilibrium or not rotate:

The Moment Clockwise = The Moments Anti-Clockwise (Refer to Figure 1c). So, F1d1 - F2d2 = 0 1 2 2 1 F d F  d ……….. (2)

Figure 1a Figure 1b Figure 1c

(4)
(5)

UNIVERSITI TUN HUSSEIN ONN MALAYSIA

Faculty of Mechanical and Manufacturing Engineering

Varignon ’s theorem can be proven easily using vector cross

product that is obey distributive law. For two-dimensional problems , we

can use the principle of moments by resolving the force into its

rectangular components and then determine the moment using a scalar

analysis. The moment is a scalar quantity,

(6)

Pulley

Weight Hook 5. EQUIPMENTS

Table 1: Principles of Moments Equipment List

No. Apparatus Qty.

1 Panel board 1

2 Pivot bar and stop ( EX5) 2

3 Pulleys ( P12) 4

4 Nuts 6

5 Screw 5

6 Weight hook ( P10) 1

7 Cord approx (40cm long) 1

8 Set of weights 1

6. PROCEDURES

1. Set up the panel board as shown in Figure 2. Ensure pivot bar is in balance and attached pulley using bolt and nut.

2.

Figure 2

Figure 2: Experiment Setup

3. Hang weight hooks from the end holes of the bar entering the hook from the back of the bar.(Refer Figure 3a). The weight of hooks each weight 0.1N.

(7)

2N 2N

d1 d2

F2 2N

d1 d2

UNIVERSITI TUN HUSSEIN ONN MALAYSIA

Faculty of Mechanical and Manufacturing Engineering

4. Add a 1.9N load to each hook to make the total of 2N.

5. Record the value of F1 and F2. Then measure and record the distance

d1 and d2.

6. Move the right hand weight hook to a hole nearer the pivot bar (Refer Figure 3b) and load it with just sufficient weighs to balance the bar in the level position.

7. Record the weight value F2 and the distance d2

8. Then, hang right hand weight hook (without weight) through pulley (refer Figure 3c).

9. Load the weight hook to balance the bar.

10. Record the weight value F2 and the perpendicular distance d2.

11. Set up the panel as shown in Figure 3d, repeat the procedure from 7 to 9 with the cord passing over the left hand pulley and attach to the lowest hole of the centre arm of the bar.

12. Fill in the Table 2

Figure 4.3a: Test 1

(8)

2N d2 F2 d1 Figure 3b: Test 2 Figure 3c: Test 3

(9)

2N

d2

F2

d1

UNIVERSITI TUN HUSSEIN ONN MALAYSIA

Faculty of Mechanical and Manufacturing Engineering

Figure 3d: Test 4

7. RESULT

1. Fill in the experimental result in the Table 2. 2. Plot a graph for .

BDA17001-2012 1 2 2 1 F d vs F d 16

(10)

Table 2: Results Moment

Test

Left Pivot Bar Right Pivot Bar Total Ratio

F1 (N) d1 (m) M1 (Nm) F2 (N) d2 (m) M2 (Nm) M1 - M2 (Nm) F1 F2 d2 d1 Figure 4.3a 2.00 0.16 0.32 2.00 0.16 0.32 0.00 1.00 1.00 Figure 4.3b 2.00 0.16 0.32 3.20 0.10 0.32 0.00 0.62 0.62 Figure 4.3c 2.00 0.16 0.32 3.50 0.09 0.32 0.00 0.57 0.56 Figure 4.3d 2.00 0.16 0.32 4.00 0.08 0.32 0.00 0.50 0.50

(11)

UNIVERSITI TUN HUSSEIN ONN MALAYSIA

Faculty of Mechanical and Manufacturing Engineering

8. CALCULATON

1. Calculate the Moment for Left Pivot Bar and Right Pivot Bar.

(12)

Moment for left pivot , M = F x d (in Nm) Figure 4.3 (a) 2N (0.16m) = 0.32 Nm Figure 4.3 (b) 2N (0.16m) = 0.32 Nm Figure 4.3 (c) 2N (0.16m) = 0.32 Nm Figure 4.3 (d) 2N (0.16m) = 0.32 Nm

Moment for right pivot Figure 4.3 (a) 2N (0.16m) = 0.32 Nm Figure 4.3 (b) 3.20N (0.10m) = 0.32 Nm Figure 4.3 (c) 3.5N (0.09m) = 0.32 Nm Figure 4.3 (d) 4N (0.08m) = 0.32 Nm

(13)

UNIVERSITI TUN HUSSEIN ONN MALAYSIA

Faculty of Mechanical and Manufacturing Engineering

Ratio of distance Figure 4.3 (a) 2 N ÷ 2 N = 1.00 Figure 4.3 (b) 2 N ÷ 3.20 N = 0.62 Figure 4.3 (c) 2 N ÷ 3.5 N = 0.57 Figure 4.3 (d) 2 N ÷ 4 N = 0.50 Ratio of distance Figure 4.3 (a) 0.16m ÷ 0.16m = 1 Figure 4.3 (b) 0.16m ÷ 0.1m = 0.62 Figure 4.3 (c) 0.16m ÷ 0.09m = 0.56 Figure 4.3 (d) 0.16m ÷ 0.08m = 0.50 9. OBSERVATIONS BDA17001-2012 24

(14)

For the test1, the distance of force for left pivot bar was equal to the distance for left pivot bar from the centre pivot bar. The force of F1 and F2 are equal, sop the total value of moment is equal to zero. Thus, it is in equilibrium.

For test2, the F1 is maintain and small than F2 because the load require for right pivot is more than left pivot to balance the pivot bar. Thus, the ratios of force and distance small. The distance of right pivot was shorter than then distance of left pivot.

All the experiment was success because the total moment equal to zero according to the theory. From my observation, the ratio of force equal to the ratio of distance. This experiment obey the principle of moment state that the moment of clockwise equal to the moment of anticlockwise.

(15)

UNIVERSITI TUN HUSSEIN ONN MALAYSIA

Faculty of Mechanical and Manufacturing Engineering

10.DISCUSSIONS

1. Discuss the graph obtained.

The graph obtain is decreasing graph. When the ratio of force smaller, then the ratio of distance will decrease. Thus, the force become larger as the distance decrease.

2. Discuss your opinion about the summation of moment from your experiment results.

Value of moment increase as the force becomes larger and as the distance from force’s line of action increase. If the line of action of F2 is perpendicular to the distance that we let, d as shortest distance between these two lines , then the moment produced by F1 has size F1d (Nm). The total moment will be zero or equilibrium when the value moment of left pivot bar are equal to the value moment of right pivot bar. ……… ……… ……… ……… ……… ……… BDA17001-2012 28

(16)

3. If the moment is nonzero, what are the factors may influence the experiment.

The factors may influence the experiment when the moment is nonzero obtain after experiment is the force of load that we set up not balance. Second, the pivot bar that we were set up not balance before we added the load. Then, the distance between the load and the centre of pivot bar not accurate because when we measure the distance, maybe there was an error. The angle of perpendicular distance not equal to 90 also can influence the moment obtain.

10.1 QUESTIONS

1. What is the principle of moment and how moments achieved?

The principle of moment also known as Vargnon’s thorem. It state that the moment of a force about a point is equal to the sum of the moment of the force’s components about the point. Principle of moments is if an object is balanced then the sum of the clockwise moments about a pivot is equal to the sum of the anticlockwise moments about the same pivot.

The moment can achieve when the distance from the line of action of the force to the pivot was obtained and its perpendicular to the force. The moment depends on the size of the force, the direction of the force and the distance from the force to the hinge. ……… ……… ………

(17)

UNIVERSITI TUN HUSSEIN ONN MALAYSIA

Faculty of Mechanical and Manufacturing Engineering

2. What does the principles of Moment state about the turning moments of forces acting on a body?

It will produce a tendency for the body to rotate about a point that is not on the line of action of the force. It is called simply the moment. The larger the force or the longer the moment arm, the greater the moment or turning effect. If the force applied at an angle, θ ≠ 90, then it will be more difficult for turning occur. It moment arm will be zero since the line of action of force will intersects to the z-axis. As the result, the moment of force about z-axis is also zero and the turning moment of forces cannot occur.

3. How to determine the moment in three dimensions body?

The moment in three dimensions body can be determine using the formula of clockwise moments equal to anticlockwise moment. You need to consider the force of three dimension bodies. You also need consider the distance of the bodies.

……… ……… ……… ………

(18)

11. CONCLUSION

Deduce conclusions from the experiment. Please comment on your experimental work in terms of achievement, problems faced throughout the experiment and suggest recommendation for improvements.

Moment of a force depends on both the forces and the location of the point about which the moment evaluated. Moment of force is equal to the sum of the moment of the components of the force after we carried out the experiment. So, the principle of moment was achieved.

The principle of moment for parallel and non-parallel forces was verified. During the experiment, the pivot bar is unbalance, so we should ensure the pivot bar is in balance before we added the load. The ratio of force and the ratio of distance must be equal after calculating them because the moment of clockwise equal to the moment of anti-clockwise. So, the graph of could be plot.

Lastly, when carrying the experiment, we should avoid the parallax error while measure the distance using a ruler.

12.REFERENCES 1 2 2 1 F d vs F d

(19)

UNIVERSITI TUN HUSSEIN ONN MALAYSIA

Faculty of Mechanical and Manufacturing Engineering

- Http://En.Wikipedia.Org/Wiki/Moment_(Physics)

-Http://Www.S-Cool.Co.Uk/A-Level/Physics/Moments-Couples-And-Equilibrium/Revise-It/The-Principle-Of-Moments

-Engineering mechanics statics, Twelfth edition, R. C. Hibbeler

Figure

Updating...

Related subjects :