Concept explainers
(a) Use of hydrogen fusion to supply energy is a dream that may be realized in the next century. Fusion would be a relatively clean and almost limitless supply of energy, as can be seen from Table 7.1. To illustrate this, calculate how many years the present energy needs of the world could be supplied by one millionth of the oceans' hydrogen fusion energy. (b) How does this time compare with historically significant events, such as the duration of stable economic systems?
Trending nowThis is a popular solution!
Chapter 7 Solutions
College Physics
Additional Science Textbook Solutions
Human Anatomy & Physiology (2nd Edition)
Biology: Life on Earth (11th Edition)
Campbell Biology in Focus (2nd Edition)
Anatomy & Physiology (6th Edition)
Microbiology: An Introduction
Fundamentals of Anatomy & Physiology (11th Edition)
- A 70-kg physicist is running up the stairs of the physics building and makes it up 48 m vertically in 1 minute. (a) what is the physicist's power output while running up the stairs? (b) if the physicist's work efficiency is just 3%, at what rate were they using metabolic energy? (c) if the physicist's metabolism can provide 5.6x10^6 J of energy before they need a rest, how long could they continue running up the stairs?arrow_forwardAs we’ve seen, the sun’s energy comes from fusion reactions that combine four hydrogen atoms to produce a single helium atom. Even in the sun’s core, where these reactions proceed most rapidly, the reaction rate is very slow, with only about 6.7 * 1013 reactions per second occurring in 1 cubic meter ofthe core. How much power is produced by these fusion reactions per cubic meter? Compare this number with the 300 W/m3 metabolic power produced by a resting reptile.arrow_forward(a) Calculate the power per square meter reaching Earth’s upper atmosphere from the Sun. (Take the power output of the Sun to be 4.00×1026W.) (b) Part of this is absorbed and reflected by the atmosphere, so that a maximum of 1.30 kW/m2 reaches Earth’s surface. Calculate the area in km2 of solar energy collectors needed to replace an electric power plant that generates 750 MW if the collectors convert an average of 2.00% of the maximum power into electricity. (This small conversion efficiency is due to the devices themselves, and the fact that the sun is directly overhead only briefly.) With the same assumptions, what area would be needed to meet the United States’ energy needs (1.05×1020 J)? Australia’s energy needs (5.4×1018 J)? China’s energy needs (6.3×1019 J)? (These energy consumption values are from 2006.)arrow_forward
- On what basis would you classify energy sources as(a) renewable and non-renewable?(b) exhaustible and inexhaustible?Are the options given in (a) and (b) the same?arrow_forwardA coal power plant has a rated output of 150 MW and a first law efficiency of 41%. Coal has an energy density of 24 MJ/kg. How many metric tons of coal are wasted by the power plant per hour while running at full capacity (that is, how much of the coal that was burned did not actually contribute to generating electricity)? Express your answer in metric tons of coal.arrow_forwardPhotosynthesis converts less than 0.5% of incoming solar radiation into new phytomass. The best annual fuelwood productivity of traditional fast-growing species (poplars, eucalyptus, pines) are no more than 10 t/ha. With the energy density of the dry wood averaging 18 GJ/t. (ha = 104 m²). Now, think about a large eighteenth-century city, which is located near a very large forest, would have required at least 20-30 W/m² of its built-up area for heating, cooking, and artisanal manufacturers. This city was totally dependent on the phytomass fuels. With the annual harvest of 20 t/ha: What is the approximate power density of the harvested phytomass fuel? (t = ton; ha = hectare) 600 (W)/(m²) 1.2 (W)/(m²) 1200 (W)/(m²) 1800 (W)/(m²) 0.6 (W)/(m²)arrow_forward
- The average electricity consumption of a house in Gainesville is known to be 1,036 kWh in a month (One month = 30 days). They would like to install solar panels of 30 % efficiency to generate this electricity. Given that the average solar power density in Gainesville is 5.47 kWh/m2/day, how much surface area must the panels occupy? Calculate the result in m² but do not write the unit. Round off you E swer to a whole number (zero decimal place.)arrow_forwardWater flows over a waterfall that is 20.0 m high at the rate of 4.0 x 104 kg/s. If this water powers an electric generator with a 40.0% efficiency, how many watts of electric power can be supplied? Give you answer in MW (1 megawatt = 1x10' W). 3,136,000arrow_forwardIf the energy in fusion bombs were used to supply the energy needs of the world, how many of the 9-megaton variety would be needed for a year’s supply of energy (using data from Table )? This is not as far-fetched as it may sound—there are thousands of nuclear bombs, and their energy can be trapped in underground explosions and converted to electricity, as natural geothermal energy is.arrow_forward
- As you will learn, carbon-14 (14C) is an unstable isotope of carbon. It has the same chemical properties and electronic structure as the much more abundant isotope carbon-12 (12C), but it has different nuclear properties. Its mass is 14 u, greater than that of carbon-12 because of the two extra neutrons in the carbon-14 nucleus. Assume the CO molecular potential energy is the same for both isotopes of carbon, and for carbon monoxide with carbon-12 atoms the frequency of the photon that causes the v = 0 to v = 1 transition is 6.42 1013 Hz and the moment of inertia is 1.46 10-46 kg · m2.(a) What is the vibrational frequency of 14CO? (b) What is the moment of inertia of 14CO? (c) What wavelengths of light can be absorbed by 14CO in the (v = 0, J = 10) state that will cause it to end up in the v = 1 level? _______µm (larger wavelength)_______µm (smaller wavelength)arrow_forwardb) A human can generate power of about 80 W. If one person works to raise water for 4 hours every day, what is the approximate volume of water that can be pumped from a 5 meter deep well in a month, assuming 50% efficiency? c) The water is to be used to irrigate a field of wheat, which requires a total of 15 cm depth of water over a three-month growing season. Using the answer from (b), how much area can be irrigated to a depth of 5 cm each month? d) If the yield of wheat is 0.1 kg/m², and the energy equivalent of wheat is 7.5 MJ/kg, what is the total energy produced by the field of wheat over a season? e) Assuming a food consumption per person of 10 MJ per day, how many person-days of food is generated by this field over a year?arrow_forwardA typical incandescent reading lamp runs at 60W. If it is left on constantly, a) how much energy (in MJ) is consumed per day, and b) what is the weekly cost (in $) if energy is charged at a rate of 12.5 cents per kilowatthour? Write your answer in two (2) decimal placesarrow_forward
- University Physics Volume 1PhysicsISBN:9781938168277Author:William Moebs, Samuel J. Ling, Jeff SannyPublisher:OpenStax - Rice University