Laboratory Report: Structure and Function (24)

M. Author, C. O. Author, and C. O. Authortwo (11)

Performed 20 November 2006; submitted 27 November 2006 (10)

Abstract-Limit the abstract to four to five sentences stating the following: (a) statement of the problem, (b) methodology, (c) pertinent results, and (d) conclusion. Avoid numbers and symbols in the abstract. After you have written the abstract, write the title. In not more than 13 words, choose a title that would reflect your abstract. To do this you may use the “variable-method” structure, e.g. “Measuring a car’s acceleration using a pendulum.” Here the variable is the gravitational acceleration and the method is the simple pendulum. Another way is to use the “dependent-independent variable” structure, e.g. “Angular displacement of a pendulum in an accelerating car.” Here the dependent variable is the angular displacement of a pendulum and the dependent variable is the car’s acceleration. Note: do not mention any keyword in the title that you will never discuss in your report. A title is a promise that you must keep. (9)

I. INTRODUCTION (8)

The main purpose of the introduction is to give a motivation for the problem in the laboratory experiment performed. There are many ways to do this. One way is to start with mention something familiar to your reader, then slowly lead him to something unfamiliar—your problem. Along the way, define the terms in the title starting from the subject to the modifiers. Let us give an example. Suppose your title is “Measuring a car’s acceleration using a pendulum.” Notice that the structure of the title is “variable-method.” Because “car” is the most familiar, begin with “car” and relate it with “acceleration”: describe what pedal to press, what then happens to your car, and end with a note that this is acceleration. Then define “acceleration” precisely. You have just finished explaining the variable part of your title and you have started with something familiar. If your reader has read this far, then you have gained his confidence that you know what you are talking about and he can relate with it. Now you go to the next step by stating your general problem: how to measure the acceleration of your car. He expects you give him something familiar again, so you say, “One way to measure the acceleration of a car is to get the difference between the readings in the speedometer between two times and then divide the result by the time interval.” This is the most obvious way and you affirm what he knows. By now your reader is getting bored seeing the same things and he is preparing to leave. So you lead him into something unfamiliar by showing that what he knows is limited. For example, you may continue as follows: “this method for measuring acceleration is valid, but it would only be useful if you were in the front seat. If you were in the back seat, there is no way that you can see the speedometer.” You are right and your reader agrees. So he asks: “How can you measure acceleration without reading the speedometer?”. He may try to guess several possibilities. If you are St. Thomas Aquinas, most likely you will list them all for him, give a critique of each one of them, and show that the procedure that you propose is superior in certain aspects. In research jargon, this is called “review of related literature,” while in business, it may be termed as “SWOT Analysis.” But since you are not yet an Aquinas or a scientist or a businessman, your teacher would only ask you to immediately state your method in one sentence: “I shall solve this problem using a pendulum: a stone tied to a string.” This ends your introduction. If your paper is long, about five to six pages, it would help the reader if you will write a short paragraph outlining the sections of your paper. (10)

II. THEORETICAL FRAMEWORK

Our skeletal frame sets the muscles and organs in our body: the skull gives the place for the eyes, the ribs for the lungs, and the pelvis for the muscles that make us stand. In a similar way, the variables in the theoretical framework give the place for the measurable and the desired quantities. The measurable quantities are those that you directly measure in the laboratory, while the desired quantities are those that are reflected in your title. For example, if your title is “Angular displacement of a pendulum in an accelerating car,” then your desired quantities are the angular displacement and the acceleration a of the car. The measurable quantities would be (a) the mass of the pendulum, (b) the angle that the pendulum makes with the vertical, and (c) the position x of the car in time t. The connection between the measurable and the desired quantities may be as short as a single equation. For example, the acceleration a of a car is related to the angle that the pendulum bob makes with the vertical:1

a = g tan , (1)

where g is the constant gravitational acceleration on the surface of the earth. See Fig. 1. Let us dissect (1) (we refer to equations by their numbers). The acceleration a is alone on the left side. Its value depends on the angle on the right side. So a is the dependent variable and is the independent variable. These two variables are defined first before the equation is displayed. After the equation is displayed, another variables is defined, in this case, it is g. Sometimes there are more of them. These variables are auxiliary variables. In theatre or film, these variables may be likened to the supporting casts: they are not the main actors but the story would be incomplete without them. (Notice that a superscipt number appears after the definition of the variables. This number refers the reader to a reference note in the Reference section at the end of the paper.) However, usually the connection between the measurable and the desired quantities is not as straightforward as in (1). So just as one goes from one building floor to another through several stair steps, one may also go from the measurables to the desired quantities through several intermediate equations.

g a Figure 1. A pendulum displaced from the vertical by an angle . The downward acceleration g of the bob is due to gravity, while the horizontal acceleration a is due to the acceleration of the frame to the right.

III. METHODOLOGY

A. Materials Give a brief description of the materials that you used, especially if they are not common. You may mention their brand name, model number, and the level of precision. You may also mention some safety precautions needed for their operations.

B. Procedure Describe the steps for measuring the measurable quantities. Write in paragraph form and not in bullets.

C. Statistical Tools Describe your equations for statistical analysis of your data. Will you use linear regression or curve fitting? Will you compute percent errors?

IV. RESULTS AND DISCUSSION

In this section you present your findings. Tell the reader that you have measured the measurable quantities. Tell him or her that you used these quantities in the equations in the theoretical framework to compute for the intermediate and desired quantities. You may summarize your results in a table, with the measurable quantities on the leftmost column and the desired quantities on the rightmost column (see Table 1). If there are too many data points, sometimes it is more appropriate to construct a graph or a figure instead, with the measurable quantities on the x-axis and the desired quantity on the y-axis.

TABLE I
QUANTITIES IN TABLE COLUMNS

Desired Quantity | Intermediate Quantity | Desired Quantity | | | | | | | | | |

V. CONCLUSION

In one or two paragraphs, give a short summary of what you did and tell the reader whether you have solved your problem or not. Where did you go wrong? Do your experimental results agree with your theoretical predictions? How can you modify your procedure to improve the validity of your experiment?

REFERENCES

[1] H. D. Young, R. A. Freedman, University Physics, 10th ed., Singapore: Addison Wesley Longman, 2002, p. 131.