Problem 3 Invent Yourself: Curved mirrors Team «12FM», Novosibirsk Kseniia Suluianova

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1 The 5th International Young Naturalists' Tournament Municipal Autonomous Institution of General Education of the city of Novosibirsk «Gymnasium 12» Problem 3 Invent Yourself: Curved mirrors Team «12FM», Novosibirsk chnmk@mail.ru Kseniia Suluianova 1

2 Statement of the Problem Suggest and demonstrate interesting experiments in which large curved mirrors can be used to heat up or cool down various objects. Investigate the possibility of using curved mirror for the needs of the population of the Siberian region Hypothesis if you send a concave mirror of large dimensions under the stream of solar rays, then their energy concentrated at the point of focus can be used to heat various objects. 2

3 Purpose to perform the melting of snow using a solar concentrator made on the basis of a concave mirror. Objectives 1. Study the theoretical justification of the phenomenon under investigation; 2. Consider the principle a solar concentrator`s operation of manufactured on the basis of a concave mirror of large dimensions; 3. Suggest a way to using a concave mirror for heating different objects; 4. Make a concave mirror of large dimensions; 5. Calculate the thermal power of concave mirrors of different diameters. 3

Theoretical Part of the Project A spherical mirror is a mirror

Optical axis The focus F of a concave mirror is a point on the

4 Theoretical Part of the Project A spherical mirror is a mirror reflecting the surface of which has the form of a sphere`s segment. Optical axis The focus F of a concave mirror is a point on the optical axis through which the ray, passes after reflection from the mirror. The ray is incident on the mirror parallel to the optical axis. Huge industrial solar oven Solar furnace, France The Second Punic War, Syracuse 4

cardboard; food foil, glue, selfadhesive tape. http://patlah.

5 Theoretical Part of the Project a d e f g h i Построение параболы To produce a concave mirror, we needed: large-size cardboard; food foil, glue, selfadhesive tape. 07/gelio/solnce_parabol_koncentrator/solnce_parabol_koncentrator.htm 5

6 Experiment 1 Purpose: to determine the thermal power of the modelled installation. Determination of the focus point by means of an electronic thermomete A black matte container with water at the point of focus Conclusion: we calculated the thermal power of the constructed installation. It is equal to 10,6 W. 6

amount of heat, J P - thermal power, W P = Q/t Formula for calculating the power of the source Q = cmτ The formula for calculating the amount of heat

7 Calculation m в - weight of water, ice, 0,1 kg m а - weight of aluminum can, 0,03 kg c в the specific heat of water, 4200 J / (kg* C) c a is the specific heat of aluminum, 920 J / (kg* C) - temperature change, С t - is the time, s λ - specific heat of melting of ice, J / kg Q - is the amount of heat, J P - thermal power, W P = Q/t Formula for calculating the power of the source Q = cmτ The formula for calculating the amount of heat needed to heat P= (c а m а τ + c в m в τ)/t P = (λm + c а m а τ + c в m в τ) t Q = λm Formula for calculating the amount of heat required for melting ice 7

Experiment 2 Purpose: to determine the thermal power of concave mirrors of different sizes. Equipment: concave mirrors, centimeter tape, thermometer, stopwatch.

8 Experiment 2 Purpose: to determine the thermal power of concave mirrors of different sizes. Equipment: concave mirrors, centimeter tape, thermometer, stopwatch. Chord length, m Segment height, m Radius of the circle, m Area of the segment, m R - radius of the circle α - central angle L - length of the chord p - length of the arc х - height of the segment S - surface area 0,3 0,03 0,39 0,074 0,15 0,01 0,286 0,018 0,24 0,04 0,2 0,5 0,37 0,13 0,197 0,161 0,91 0,11 1 0,

9 Experiment 2 Purpose: to determine the thermal power of concave mirrors of different sizes. Area of the segment, m Chord length, m Time, minutes Thermal power, W Power per unit area, W / m2 0,018 0, ,8 544,4 0,5 0, ,4 24,8 0,074 0, ,6 264,9 0,161 0, ,1 273,9 0,691 0, ,6 15,4 Conclusion: mirrors having different parameters can concentrate different thermal power. 9

10 Experiment 2 The ambient temperature is + 3.4С, the wind SW 5 m / s. 10

11 Experiment 3 Purpose: to effect the melting of snow by means of a concave mirror. The air temperature is + 7 C, Wind NE 3 m / s. After 18 minutes 15 seconds 11

12 Experiment 3 We calculated the thermal power of the solar concentrator. It is equal to 30 W. The intensity of the heat flow - the heat flow, per unit area of the concave mirror is about 400 W / m2. (The power was divided by the surface area of the concave mirror). With increasing the surface area and the time of using of the solar concentrator at the same time reducing the height of the segment of the concave mirror (so that the focus leaves the mirror) we can melt snow in hard-to-reach places. 12

13 Conclusion 1. We consider the principle a solar concentrator`s operation of manufactured on the basis of a concave mirror of large dimensions. 2. Large mirrors (from 10 to 100 cm) were produced. 3. According to the experiments carried out, the thermal power of the concave mirrors of different diameters was calculated. 4. On the basis of formed and industrial concave mirrors, a mobile snow melting unit has been developed. 13

14 References 1. Landsberg G.S. «Elementary textbook of physics» Moscow: Fizmatlit, T. 3. «Oscillations and waves. Optics. Atomic and nuclear physics.» 3. Aksenovich L.A. «Physics in high school: Theory. Tasks. Tests: Proc. Allowance for institutions that provide access to the Society.» 4. ol_koncentrator.htm 5. Modern anti-avalanche systems // 6. Modern engineering systems of protection against snow avalanches in the world. Analysis of various technologies // 7. Murtazov A.K. Ecological monitoring. Methods and means. Part 1. Textbook, the Russian State University. S.A. Yesenin, Ryazan, Isaeva L.K. Fundamentals of environmental safety in natural disasters. - Moscow: Academy of State Fire Service of the Ministry of Emergency Measures of Russia,

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