UNIVERSITI TEKNOLOGI MARAFAKULTI KEJURUTERAAN KIMIACHEMISTRY LABORATORY(CHE 175)

NAME : ABDUL HALIM BIN NORDIN (2008293172) MUHAMMAD RAZI BIN ZAHARI (2008424824) NOOR SYAFIQAH AMERAH BT AHMAD TARMIZI (2008293072) SITI NOR SAMRAH BT A.RAHIM (2008291992) NURUL ADILAH BT NASARUDDIN (2008292022)GROUP : 2EXPERIMENT : HOOKES LAWDATE PERFORMED : 11 FEBRUARY 2009SEMESTER : DIS 2008 APRIL 2009PROGRAMME/CODE : DIPLOMA IN CHEMICAL ENGINEERING / EH 110

NoTitleAllocated Marks (%)Marks (%)

1.Abstract/Summary5

2.Introduction5

3.Aims/Objective5

4.Theory5

5.Procedure3

6.Apparatus5

7.Results20

8.Calculations10

9.Discussions20

10.Conclusions10

11.Recommendations5

12.References5

13.Appendices2

Total100

Remarks :

Checked by : Rechecked by :

SUMMARY/ABSTRACT

Any spring has a natural length at which it exerts no force on the

mass,m. The position of the mass at this point is called the equilibrium

position. If the mass is moved either up, which compresses the spring, or

down, which stretches it, the spring exerts a force on the mass to equilibrium

position. The objective of this experiment is to determine the relationship

between the force and the displacement of a spring. The experiment was

starting with using 4N/m spring constant. The experiment started from 4

masses on the hanger then it continue with 8 N/m with a constant spring.

When experiment has done,it can be conclude that this experiment follows the Hooks Law which Hooks Law states that the spring exerts it force in the direction opposite the displacement, acting to return it to its natural length oof spring also increase. But each spring has a spring constant to show its capability to support the mass. When the mass is greater than spring constant , spring will be lose elasticity.Consequently,spring can return to natural length and maintain that form.

INTRODUCTION

When an object vibrates or oscillates back and forth , over the same path , each vibration taking the same amount of time , the motion is periodic. The simplest form of periodic motion is represented by an object oscillating on the end of a uniform coil spring . Because many other types of vibrational motion closely resemble this system , we will look at it in detail.

We assume that the mass of the spring can be ignored, and that the spring is mounted horizontally, so that the object of mass m slides without friction on the horizontal surface. Any spring has a natural length at which it exerts no force on the mass m. The position of the mass at this point is called the equilibrium position . If the mass is moved either to the left , which compress the spring , or to the right, which stretches it, the spring exerts a force on the mass that acts in the direction of turning the mass to the equilibrium position; hence it is called a restoring force .

We consider the common situation where we can assume the magnitude of the restoring force F is directly proportional to the displacement x the spring has been stretched or compress from the equilibrium position:

F = -kx

Note that the equilibrium position has been chosen at x = 0. Equation which is often referred to the Hook's law, is accurate as long as the spring is not compressed to the point where the coils are close to touching or stretched beyond the elastic regionOBJECTIVES

The objectives of this experiment is to investigate the relationship between the force and the displacement of a spring. We will determine the spring constant, k , for an individual spring using both Hookes Law. Secondly, this experiment is also conducted to see whether the spring constant gives any effect on the value of displacement.

THEORY

If a weight, W=mg, is hung from one end of an ordinary spring, causing it to stretch a distance x, then an equal and opposite force,F, is created the a spring which acts to oppose the pull of the weight. If w is not so large as to permanently, distort the spring, then the force,F will restore the spring to its original length after the load is removed. F is thus is called an elastic force and it is well known that the magnitude of an elastic force and it is well known that the magnitude of an elastic restoring force is directly proportional to the stretch.

F=kx The relationship is called Hookes Law

The constant k, is called the spring constant, or stiffness coefficient. An additional approach is possible. One definition of simple harmonic motion (SHM) is that it is motion under a linear, Hookes Law restoring force. For such a motion it have from Newtons Second Law.

F= -kx = ma

The minus sign appears since in this case the acceleration of the object in SHM is in the direction opposite to the force causing it where k is again the spring constant and m is the mass which under motion and a refers to gravitational force where it is equal to 9.81m/s^2. The provides an additional method for testing whether the spring obeys Hookes Law.

PROCEDURES

1. The hanger was hang assembly on the notch of the Hookes Laws apparatus.2. The scale was adjusted vertically, so that the 0cm mark is parallel to the disc.3. 3 to 4 masses has been hang on the hang such that the total displacement of the ring is not greater than 10cm but not less than 2cm. this total mass which included both masses and hanger has been entered with the corresponding displacement in the data in Table1.

4. one mass has been removed and the new data and total mass and the corresponding displacement has been entered.

5. The previous step has been repeated until all masses has been removed.6. steps 3-5 was repeated with different spring and all values has been entered into data in Table 2

APPARATUS

Disc

Hanger

Hooke,s Law Apparatus

Two types of spring (4N/m and 8N/m)

Mass set (10g and 20g)

RESULT

4N/mData table 1# of massesDisplacement (cm)Total Mass (g)

45.040

33.730

22.020

10.410

8N/mData table 2# of massesDisplacement (cm)Total Mass (g)

46.580

34.560

22.540

10.520

ANALYSIS4N/mAnalysis Table 1Displacement (m)Force (N)

0.0500.200

0.0370.148

0.0200.080

0.0040.016

8N/mAnalysis Table 2Displacement (m)Force (N)

0.0650.52

0.0450.36

0.0250.20

0.0050.04

CONCLUSIONS /QUESTIONS

1. In general, what pattern do you notice between the force due to gravity of the masses and the displacement of the spring?

2. Starting with y=mx+b, write an equation that represents the relationship between force and displacement. Dont forget to include units on all number!

3. What is the physical meaning of the slope for the force-displacement graph? (hint : look at the units!)

4. What is the physical meaning of the vertical intercept for the force-displacement graph?

5. Using this equation, what would be the force required to stretch the spring 10 cm?

6. What would be the displacement of a 100g mass?

ANSWER FOR THE QUESTION:

1. The force due to gravity of the masses and the displacement of the spring is linear.2. Calculation: Using the equation y=mx+b

y= forcex=displacement of the springm=spring constantb=interception

using 8N/m spring: y=0.200N, x=0.050, m=8.0y=mx+b0.200=8(0.050)+bb=-0.2N

The equation for spring 8N/m:y=8x-0.2

using 4N/m spring:

y=0.52 N, x=0.065, m=4.0y=mx+bo.52=4.0(0.065)+bb=0.026N

The equation for spring 4N/m:y=4x+0.0263. From the graph, physical meaning is the force due to gravity of the masses over displacement of the spring. It mean that, the slope is spring is constant, k.4. H mean that the spring have loosen its strength because it had been use many time before and rate of error is higher.5. y= 8x-0.2 =8(0.1)-0.2 =0.6N

y=4x+0.026 y=4(0.1)+0.026 =0.426N

6. y=8x-0.20.6=8x-0.2x=0.1m

y=4x+0.0.260.426=4x+0.026x=0.1m

DISCUSSION

As we know in hookes Law it states that the restoring force of a spring is directly proportional to a small displacement. In equation form, we write (F=kx). Where F is the force, k represent spring constant and x is the size of displacement. The proportionality constant k is specific for each spring. The main objective of this is to determine the spring constant k. Displacement is measured in meters. We use the value of 50g, 40g, 30g, and 20g for both spring constant 4 n/m and 8n/m.

Note that the restoring spring force is given by hookes Law as kx. This equilibrium can be expressed as : F=Kx

Since F is the weight of the added mass; Therefore, the spring constant k is the slope of the straight line F versus x plot.

Force is mass times the acceleration of gravity or W=mg where g is about 980 cm/sec or 98. Using this relationship force are computed for the masses in the table above. Data from this table are plotted on the graph.

As stated above the relationship depicted on the graph is W=kx where k is the spring constant. Therefore, the spring constant is the slope of the line. So, we get the value of 6.25N/m and 7.29N/m for the spring constant. Basically our experiment can prove the hookes Law. In other hand this also prove that our experiment had been done successfully.

In this experiment, there are two problem that can be happen or the precaution that can be concern with. Firstly, before start this experiment we must check first whether the spring that we will use are in good condition before the experiment so that the experiment run smoothly. Other than that is when reading the scale of the spring, where our eye should be parallel with the scale to avoid parallax error occur while taking the readings. Besides, we must take the correct decimal places for all the value of the results in order to get a precisely reading.

RECOMMENDATION

1. Make sure the spring in good condition.

2. The eye of the reader should be parallel to the reading.

3. Make sure that the spring that hanged the mass did not bouncing when reading the scale because it might affect the readings.

4. Take the correct decimal places for each reading.

5. Students must understand and go through the lab manual first before doing the experiment.

6. Students must have overall overview about the experiment.

7. The experiment should be done in a closed air room to avoid any air resistance that will influenced the readings of the scale.

REFERENCE

PHYSIC GIANCOLI (SIXTH EDITION) DOUGLAS C. GIANCOLI

MANUAL LAB ENGENEERING PYHSICS LABAROTORY (CHE 175)

PROGRAM MATRIKULASI MODUL FIZIK EDISI PERTAMA 1999 PROF. MADYA DR. ELIAS SAION PROF MADYA DR. AZIZAN ISMAIL

APPENDICES