BFM2821 Mechanics Laboratory

Lab Title : Principle of moment

Category : Static

Group Member :

1. Nur Qamarina Binti Zaudi FB09043

2. Sarina Binti Shafie FB09066

3. Radhiah Binti Abd. Razak FB10051

4. Muhammad Iqbal Bin Jafar FB09035

5. Ahmad Fathi Bin Mohd Zainuddin FB09041

Lab Instructor : En. Fakhrul Anuar

1.INTRODUCTION

When a force is imparted to turn an object, it generates moment. It is measured by the product between the force (F) and the perpendicular distance (d) between the pivot and the line of force. The product F x d is known as moment of the force. The principle of moments is often used in engineering and construction where forces have to be balanced to prevent turning. This concept applies for both parallel and oblique forces. Nevertheless, the distance, d should always be perpendicular from the pivot.

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

forces.

2.APPARATUS

3.PROCEDURE

3.1 Preparation

1. The mounting panel was secured in the vertical position.

2. The beam balance (pivot bar) was mounted through the hole on the panel with the pivet

screw, and was secured with nut. The stop bar has been sured horizontal ad above the pivot

bar (see Figure 1).

3. The pulleys was positioned on the panel and them was secured with nuts.

3.2 Test 1

1. The weight hooks was hung from the end holes of the bar (see Figure 2). The hook was

inserted from the rear of the bar.

2. The weight of each weight hook is 0.4N. 1.6N load was added to each of them to obtain a

total of 2N force at both side of the bars.

3. The arm “floating” was positioned between the stop.

4. The distance of the weight hooks was measured from the pivot of the bar (the reading is

160mm).

5. The right weight was hook was moved to a hole nearer to the pivot, and was loaded with

sufficient weights to balance the bar in the level position ( see Figure 3).

6. The total weight at the weight and the total loads, F was recorded.

7. The distance, d of the hole from the pivot was recorded.

3.3 Test 2

1. A cord with (approximately 40cm long) was taken. The right weight hook was removed from

the bar.

2. The cord was passed over the middle pulley and was hooked into the end hole of the right

arm of the bar (Figure 4) using the lightweight hook.

3. The weight hook was loaded to balance the bar. The weight of the weight hook and its load,

F was recorded.

4. The perpendicular distance, d from the pivot to the cord was recorded.

5. The test was repeated by passing the cord over the left pulley and was attached to the

center arm of the bar (Figure 5).

4. Results

Table 1: Data collected from the experiment

Experiment

Type of force

Force, F (N)

Distance (measured from

the pivot point), d (m)

Moment, M (Nm)

Test 1

Tension

Left : 1.85 Left : 0.010 Left: 0.0185

Right : 2.00 Right : 0.016 Right : 0.032

Test 2

Tension

Figure 4 : 2.35 0.010 0.0235

Figure 5: 5.85 0.006 0.0351

5. Discussions:

Turning moment was measured by multiply Force acting on a body and

perpendicular distance between force and pivot.

M = turning moment

F = Force acting on a body

r = distance from pivot

Principle of moment state that the moment of any force is equal to the algebraic

sum of the moments of the components of that force.

6.Conclusion:

A rigid body will remain in equilibrium provided the sum of all the external forces acting on

the body = 0 and sum of moments of the external forces about a point = 0