Act15_sol - 2/24/05 Activity 15 Solutions: Energy in Nature...

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2/24/05 1 Activity 15 Solutions: Energy in Nature 15.1 The Earth-Sun System 1) Energy from the sun Observe the models of the Earth, Moon, and Sun in the room. a) Imagine that the distance between the Earth and the Sun is represented by the length of a football field (100 yards or 91 meters). Choosing this distance to set the scale, the Sun, at one goal line, is represented by a ball 85 cm in diameter (the size of a large beach ball or exercise ball). What would be the diameter of a model of the Earth at the opposite goal line? 8 mm (about the size of an M & M candy) What would be the diameter of a model of the Moon? _ 2 mm_ How far would the model of the Moon be from the model of the Earth? _ 23 cm _ b) It takes radiation from the Sun about 8.3 minutes to reach the Earth. How far away is the Earth from the Sun? m 10 x 55 . 1 min) / s 60 x min 3 . 8 ( x ) s / m 10 x 3 ( t S D or t D S 11 8 = = = = 2) How much energy does the Earth receive from the Sun? a) How many watts of energy does the Sun produce? _ 3.90 x 10 26 watts _ b) Only a small fraction of this energy actually reaches the outer atmosphere of the Earth. If this energy is about 1.76 x 10 17 watts, what percent is this of the total energy produced by the Sun? % 000000045 . 0 % 10 x 5 . 4 10 x 5 . 4 watts 10 x 90 . 3 watts 10 x 76 . 1 8 10 26 17 = = = c) Where does the rest of the Sun’s energy go? The energy radiates out into space uniformly all directions. Only a tiny fraction of the Sun’s energy is intercepted by the Earth. d) What is the source of the Sun's energy? nuclear fusion reactions in which hydrogen is converted into helium 3) What form of energy is received from the Sun? a) What form of energy does the sun give off? The sun gives off electromagnetic radiation with a frequency (or wavelength) centered on that of visible light.
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2/24/05 2 b) We now review the spectrum of a light bulb filament at different temperatures. Look at the filament through a diffraction grating. Describe any changes you see in the spectrum as the filament glows hotter. The red end of the spectrum is more prominent when the light is not as bright (the filament is less hot). The blue end of the spectrum becomes more prominent as the light becomes hotter (by adjusting the light to be brighter). c)
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This note was uploaded on 06/11/2011 for the course PHYSICS 104 taught by Professor Staff during the Winter '11 term at Ohio State.

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Act15_sol - 2/24/05 Activity 15 Solutions: Energy in Nature...

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