Illinois Junior Academy of Science - Yearbook (Urbana, IL)

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1 g5.sr. x PNG..- u.'.5 'M - JS.. U., 1 16.501 1 5 5 o U UI eu RSSB C5106 umm H o CNRS ' Mo X The magnitude bfwffhe deflection at the rear of the chassis when the wheels actually do strike the obstruction on the ro- tating drum is recorded by means of a spring aluminum pen arm attached to the rearmost chassis member. The pen arm is reinforced with wood except at the very end to reduce tor- sion caused by the friction of the pen on the recording paper. The writing instrument is a felt marker with a very fine point. It records on paper mounted on a rotating drum placed to the side of the chassis. lnqflah uasem N--' I 1 gqaflnca ..L'!' Gam QQ MOTU'- , - Posrpuu GNU r.oNs1ilvc1 9? fl-Grefkbws DY-Oh frfc-r g To QQCALQX The recording drum consists of a hollow sheet metal cyl- inder, open the bottom, which is fastened to a rotating shaft. The shaft is supported by a bearing and is driven through an 8:1 gear reduction from a small, low speed electric motor. The chassis itself is a simple perimeter type with cross bracing. It is constructed primarily of 56 square spruce strips glued and nailed together. The two wheels riding on the drum turn on two half-axles which are independently sprung, each pivoting about a pin slightly offset from the center of the chassis. Each half-axle is sprung by a coil spring and located fore-and-aft by wood strips forming a channel which limits axle motion to the vertical. wana str-WS X SPW5' Quoy SUSPGNSIDIJ frm 10 seated AX,-Q gent WWW Sine who In later experimentation, the rubber tired wheels which were used originally were replaced with metal wheels. The half-axles used with these new wheels were thinner than the old ones so the simple channel which had previously located the axles for-and-aft was no longer effective. The suspen- sion was therefore modified slightly with the introduction of control arms to locate the axles. These control arms pivoted with the axles about a point directly in front of the axle pivot. nv Wm svsveusmvl cemtut Aan Pm I MDIHI'-ICFTIUNS 1' get mee- no-r 10 stud ' mt Qwot- U game as HW?-6. Another modification which was made in later experi- ments was the addition of shock absorbers or more cor- rectly, dampers, consisting of strips of wood which introduced additional friction into the suspension by pressing against the axle. There were located on the outside of the wheels and pressed on that part of the axles which extended beyond the wheels themselves. The dampers were located by a yoke which ran across the width of the chassis. L., I ibut! TOY elw.vnS1?4Nv.:bvL vue-J 9 lv 5 HJ: R... 1 .Sa After a small tray of weights was added to the left side of the chassis to balance the pen arm on the right, a box-like carrier was mounted on the chassis into which weights could be taped to vary the mass of the chassis. A number of nearly identical lead weights were cast and numbered for identification. A light bar was passed through the axle channels and either end was placed on the pan of a balance at equal distances from the center of the chassis. The front of the chassis was supported, and the weights added in pairs in a standard order. The mass supported by each balance for increasing numbers of weights were as follows: Weight No.'s Mass on each balance none added 160 g. 1-2 191 1-4 221 1-6 251 1-8 280 1-10 311 1-12 342 1-14 372 Fourteen weights was the maximum load used in experimen- tation because greater numbers of weights placed dangerous strain on the apparatus as the chassis crossed the obstruc- tion. Since for a coil spring AQ Q K AF where K is some constant,A1.. is the change in length of spring, and A F is the force applied to the, spring, a single measurement of the compression caused by a known force will give the spring constant. The following apparatus was used to determine the values for K for springs used in the experiment: -1 mnovnw- 'LGU :muff WU? Masons 9 Mmpu. RT gawutvauw-5 wsmuasic -T-1...-- M555 gf,,,.,u. muowh' The springs which were tested in this manner were found to have spring constants of 3.78, 4.87, 6.38, 25.8, 36.8, and 110 newtons! centimeter. Springs which were shorter than the standard length of 3.00 cm. were lengthened with wood blocks glued onto one end, while the one that was longer than 3.00 cm was cut. 3.00 cm was chosen for the standard length because it gave the least camber variation from zero, i. e., slightly positive under light load and slightly negative under heavy load. Springs were mounted by passing a loop of adhesive tape through the last coils at either end of the spring. The tape in turn was passed around the chassis member directly above the axle just inside the wheel and also around the axle to hold the spring securely in place. 1596 TAPE -stew. M00 5Tl ' 'Q

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sensitivity, a liquid seismograph could be made to record re- sults in a very orderly and readable fashion. There is one fallacy in the experiments described above. The waves produced by movements inside the earth are dif- ferent from those produced by slight pressure on a table, the device used for producing small movements in the laboratory. If the results reported above are to be considered in evalu- ating the liquid seismograph, it must be assumed that the results would be similar using natural waves in place of movements produced artificially. The ultimate test of this new seismograplmic principle will be its ability to detect and identify actual earth movements, and actually, the principle will not be thoroughly tested until it is used for this purpose. The development and evaluation of the liquid seismo- graphic principle has just-begun. To date the only liquid tested has been water, and experiments will soon be run using liquids of varying viscosity. It is hoped that the mir- ror system can be improved upon, using knife-edge bearings and very lightweight material. Eventually, a complete seis- mograph will be built, completely enclosed in a lightproof box. A drum covered with photographic paper will be ro- tated by a synchronous motor, and will record the faint light beam reflected from the mirror apparatus immersed in the liquid. Hopefully, this seismograph will then be tested re- cording actual earth movements, with a standard seismo- graph acting as a control. Sultito Coordination Compounds STEVEN BINDER Niles Township H. S. North Sponsor - Mr. Frank Cardulla ABSTRACT Our understanding of sulfite ion chelation has changed rapidly in the last ten years. It had always been assumed that this ion could act as a bidentate ligand, bonding through two oxygen atoms. Recently, though, spectrophotometric data has suggested that the ligand actually forms a bridge between metal ions, using oxygen and sulfur. Two com- pounds which apparently have such a structure are di-JL - sulfitotetrakisethylenediaminedicobalt CIIIJ chloride and po- tassium di-J-L -hydroxo-J-A -sulfitodisulfitotetraaquodichro- mate CIIIJ. My paper discusses application of this and other recent developments to other sulfito coordination compounds. The several LMKSOXLJ3 complexes exhibit unusual sta- bility and insolubility. An excellent explanation for these properties would be a polynuclear structure. My paper dis- cusses various possible structures and how the true structure could be determined. I also reinterpret the isomerism of the ICIOCNHQASOQJ , using knowledge of the large trans- effect of the sulfito ion. The aminosulfito series is compared to the aminocarbonato series, wihose reactions are better known. Finally, the optical activity of all these compounds is discussed in detail. The Physiological Role of Stomata in Photosynthesis JAN LAURIDSEN Thornridge High School Dolton My project is primarily concerned with the function of stomata and exactly how they affect the leaf. A basic under- standing of their function was not difficult to achieve since a number of books have been written on this subject: butt in order to truly comprehend their relation to the entire leaf, af number of experiments were necessary. I selected the variable for may experiments by deter- mining whioh factors are directly related to stomatal ac- tivity. Of these factors involved, I chose temperature, hu- midity, and carbon dioxide. My first experiment, of course, was conducted under normal conditions, so that comparisons could be made later. My second experiment, however, involved temperature. I began by placing fourteen species of plants in total darkness for a period of two days. This step proved necessary in order to remove most of the starch from the leaves. I then placed the plants in an abnormal environment of 38' C. after coat- ing several leaves with petroleum jelly. The first leaf was coated on the upper epidermis, the second on the lower. The third leaf was coated on both epidermi, and the fourth was left uncoated. After a period of 1 day in a lighted area, the leaves were tested for starch. I noted that the amount of photosynthesis was greatly reduced under severe temperature change. I conducted several similar experiments with different variables. I used raised 'humidity by placing the plants in terraiums which had been previously filled with water. I also lowered the humidity by placing the plants in dessicators. My last experiment concerned carbon dioxide. Again I placed the plants in the terrariums, but this time I added a mixtLu'e of hydrochloric acid and 2.97 grams of Na,Cos, multiplying the normal concentration or carbon dioxide 1.03 per centl by a factor of five, which resulted in .15 per cent. As a result of my experiments, I have come to one basic conclusiong that all plants must be considered individually. Although general statements can be made concerning stoma- Eal behavior, biological variation remains the dominating orce. The Effects ot Spring Constant and Chassis Mass on the Average Amplitude ot Chassis Bounceis an Independent Rear Suspension System STEVEN CARHART Lyons Township High School LaGrange STATEMENT OF PURPOSE The purpose of this project is to find quantitative rela- tionships among the average amplitude of chassis motion at the rear of a one-eighth scale automobile encountering a series of obstructions, the mass supported by Uhe rear wheels, and the spring constant of the coil springs in the suspension. APPARATUS USED The somewhat unusual nature of the apparatus designed for this experiment makes a brief description of it before pro- ceeding desirable if not mandatory. The apparatus is of original design and consists of a onc- eighth scale automobile chassis mounted in such a way that the rear wheels rest on a rotating 'hollow metal drum on which obstructions of various sorts may be mounted across the path of one or both wheels. In experimentation, the ob- structions usually struck both wheels simultaneously rather than only one wheel to eliminate chassis torsion as a factor in determining the amplitude of dhassis bounce. The front of the chassis is supported by two pins stuck into the end chassis member from side supports: the chassis pivots about these two pins. The stationary front of the chassis may be considered to approximate a front suspension system which has encountered a bump soon to hit the rear, feacted to it, and brought the front of the chassis to equi- ibrium. 1

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PROCEDURE Six pairs of springs of varying spring constants were mounted in turn on the chassis. The lead weights were added to the chassis in pairs up to a total of fourteen weights for each spring constant, giving forty-eight combinations of weights and springs Cincluding no weights with each of the pairs of springsl that were tested. The large drum on which the rear wheels of the chassis rest was allowed to run at a constant speed of 36 scale m.p.h. and the effect of the bump mounted on the drum on the chassis was recorded by the pen arm attached to the chasis. The pen recorded a series of regular oscillations in most tests. Care was taken to be sure that the chassis assumed a regular pattern before the re- corder was turned on if at all possible and that the pen arm touched the recording drum at the same point on every trial. Trials were made with the obstacle on the drum a long bar of 56 square spruce encountered by both wheels at the same time and also with a shorter bar encountered only by the right wheel. The deflection of the chassis in each particular encounter with the obstruction was recorded by the pen arm, measured, and averaged with other values taken under the same con- ditions. Since each impact produced one immediate high peak and then a minimum height as the chassis fell back to the road and the springs were compressed, the deflection to be measured, hereafter referred to as d, was arbitrarily but meaningfully defined to be the vertical distance from 1. . H-. . H, M- wr-U-8 Q 'kb'-'5EuTZ5FETi'8'w '-' the highest point after impact to a line drawn between the two adjacent minima. CRefer to figure.J Generally, one run consisted of one rotation of the recording drum and produced between fifteen and twenty separate values of d to be averaged. In trials where many weights were added, the additional drag on the large drum occasionally caused the motor to slow. In these instances, the motor was assisted to maintain standard speed through the use of a hand crank. The disappointing results of this first series of experi- ments led to a re-examination of the degree of control which had been exercised over the variables. Two possibilities arose: the tires on the vehicle were elastic to some degree: perhaps they absorbed enough of each impact to throw off the data. The nature of the obstruction used also came under scrutiny. The possibility that a more gradual obstruc- tion for the wheels, perhaps with a semicircular rather than a square cross-section would provide better data was also considered. Accordingly, the rubber tires were replaced with metal wheels and the square obstruction with a semicircular one. Again the mass was varied while spring constant re- mained at 4.87 ntfcm, but the amplitudes which were av- eraged failed to suggest any meaningful relationship between the mass of the chassis and d for a given spring constant. Then it was observed that, due to the varying natural fre- quencies attained by the chassis as mass increased, the har- monic motion which the chassis undergoes between impacts, was placing t.he chassis in a slightly different phase of har- monic motion at each impact, depending on the mass, thus producing different amounfts of residual vibration which were added to the fresh impact. Thus, changing mass values introduced another variable, the amount of residual harmonic motion, which was not being controlled. To remedy this situation, additional friction was intro- duced into the suspension system in order to gradually de- crease the residual harmonic vibrations after the initial im- pact and bring the chassis back to equilibrium before the following impact. In this way, the state of the chassis rela- tive to the suspension, which had been varying and possibly obscuring meaningful data, could be made constant before each new impact. The method chosen to introduce this fric- tion was the use of wood strips which pressed against the axles and rubbed against the axles as the chassis vibrated. Tests with varying masses and spring constants were re- peated in the manner previously described after the chassis had been thus modified. However, measurements of d still did not show any clear pattern even after the major chassis modifications were made. It was noted, though, that the distance from the high- est point reached Cimmediately after impactl to the position of the chassis immediately before impact CAfter the instal- lation of the shock absorbers or wood strips, the chassis usually was nearly at equilibrium, that is, without any resi- dual motion, just before impact.l exhibited a definite de- creasing trend as the mass increased. This quantity was designated as c and was measured for as many combina- tions of springs and weights as was possible. -9- Quatre-tom DEFHHTQDN or Q. . RESULTS Average values of d for the various combinations of spring constants and chassis mass supported by each spring and wheel Cone half the total chassis mass supported over the drum road J with the obstruction a long square cross- sectioned bar encountered simultaneously by both wheels were as follows: Chassis mass C8-J No. of over weights each Spring Constant, K lntlcml used wheel 3.78 4.87 6.38 25.8 36.8 110 0 160 1.72cm 2.42cm 1.91cm 1.92cm 2.92cm 5.88cm 2 191 1.35 0.90 2.92 1.78 2.60 4.85 4 221 1.46 2.42 4.03 1.62 1.57 4.85 6 251 1.37 1.26 5.92 1.79 1.89 5.62 8 280 2.66 1.12 8.28 2.35 1.37 3.64 10 311 3.28 0.85 7.85 2.49 4.28 3.93 12 342 3.34 1.23 8.22 2.44 5.19 3.73 14 372 4.44 1.65 8.85 2.52 6.03 3.54 Before the friction-inducing wood strips Cwhich function in the same capacity as shock absorbers on an actual autol, metal wheels, and semicircular obstructions were added to the apparatus, data was taken in which the square cross- section bump was encountered by only the right wheel. The pen arm, moving through an arc, made traces from which d was measured. -5----'. - 13' KH HRM PKC ul-ni Smart GDM? These measurements yielded the following average values: No. of weights Chassis mass fg.l d Ccml used over each wheel lK:36.8 ntfcml 0 160 6.10 2 191 5.93 4 221 5.63 6 251 5.93 8 280 5.85 10 311 5.81 12 342 5.58 14 372 5.69 Data were measured for only one value of K as no meaning- ful pattern emerged, suggesting that laboratory time might be better spent varying conditions in order to hit upon co- hesive data rather than exhaustively investigating an un- promising situation. Data traces were made for all springs, but an examination of the traces confirmed the suspicion that measuring these data would be a waste of time. Data taken last year under apparently identical circumstances conformed to a smooth exponential curve: however, inability to repro- duce these values strongly suggests that the validity of these previous data is at best doubtful. After the metal wheels and semicircular obsruotion were added to the apparatus, data traces were made with the standard combinations of weights and springs, with the obstruction striking either both wheels or only the right. As before, an examination of the data traces suggested no trends or regularities as mass was increased for a given spring, so time-consuming measurements were dispensed with and the shock absorbers mounted. Data taken with the shock absorbers in place exhibited a definite decreasing trend as chassis mass was increased, so careful measurements of the data traces and averages were computed. It should be noted that the quantity which showed this regularity was not d, which had been measured in previous experimentation, but