One goal of the Russian space program is to illuminate dark northern cities with sunlight reflected to the Earth from a 200-m diameter mirrored surface in orbit. Several smaller prototypes have already been constructed and put into orbit. (a) Assume that sunlight with intensity 1 370 W/m2 falls on the mirror nearly perpendicularly and that the atmosphere of the Earth allows 74.6% of the energy of sunlight to pass though it in clear weather. What is the power received by a city when the space mirror is reflecting light to it? (b) The plan is for the reflected sunlight to cover a circle of diameter 8.00 km. What is the intensity of light (the average magnitude of the Poynting vector) received by the city? (c) This intensity is what percentage of the vertical component of sunlight at St. Petersburg in January, when the sun reaches an angle of 7.00° above the horizon at noon?
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Chapter 33 Solutions
Bundle: Physics for Scientists and Engineers, Volume 2, Loose-leaf Version, 10th + WebAssign Printed Access Card, Single-Term
- A uniform circular disk of mass m = 24.0 g and radius r = 40.0 cm hangs vertically from a fixed, frictionless, horizontal hinge at a point on its circumference as shown in Figure P34.39a. A beam of electromagnetic radiation with intensity 10.0 MW/m2 is incident on the disk, in a direction perpendicular to its surface. The disk is perfectly absorbing, and the resulting radiation pressure makes the disk rotate. Assuming the radiation is always perpendicular to the surface of the disk, find the angle through which the disk rotates from the vertical as it reaches its new equilibrium position shown in Figure 34.39b. Figure 34.39arrow_forwardWhat is the intensity of an electromagnetic wave with a peak electric field strength of 125 Vim?arrow_forwardThe electric part of an electromagnetic wave is given by E(x, t) = 0.75 sin (0.30x t) V/m in SI units. a. What are the amplitudes Emax and Bmax? b. What are the angular wave number and the wavelength? c. What is the propagation velocity? d. What are the angular frequency, frequency, and period?arrow_forward
- A possible means of space flight is to place a perfectly reflecting aluminized sheet into orbit around the Earth and then use the light from the Sun to push this "solar sail." Suppose a sail of area A = 6.90 x 105 m2 and mass m = 5,000 kg is placed in orbit facing the Sun. Ignore all gravitational effects and assume a solar intensity of 1,370 W/m?. (a) What force (in N) is exerted on the sail? (Enter the magnitude.) (b) What is the sail's acceleration? (Enter the magnitude in um/s2.) |um/s? (c) Assuming the acceleration calculated in part (b) remains constant, find the time interval (in days) required for the sail to reach the Moon, 3.84 x 10° m away, starting from rest at the Earth. days (d) What If? If the solar sail were initially in Earth orbit at an altitude of 400 km, show that a sail of this mass density could not escape Earth's gravitational pull regardless of size. (Calculate the magnitude of the gravitational field in m/s².) m/s2 (e) What would the mass density (in kg/m2) of…arrow_forwardA community plans to build a facility to convert solar radiation to electrical power. The community requires 2.60 MW of power, and the system to be installed has an efficiency of 30.0% (that is, 30.0% of the solar energy incident on the surface is converted to useful energy that can power the community). Assuming sunlight has a constant intensity of 1 200 W/m2, what must be the effective area of a perfectly absorbing surface used in such an installation?arrow_forwardSunlight reaches the ground with an intensity of about 1.0 kW/m2 . A sunbather has a body surface area of 0.8 m2 facing the sun while reclining on a beach chair on a clear day. (a) how much energy from direct sunlight reaches the sunbather’s skin per second? (b) What pressure does the sunlight exert if it is absorbed?arrow_forward
- The intensity of solar radiation that falls on a detector on Earth is 1.00 kW/m2. The detector is a square that measures 5.11 m on a side and the normal to its surface makes an angle of 30.0° with respect to the Sun’s radiation. How long will it take for the detector to measure 424 kJ of energy?arrow_forwardThe average intensity of sunlight on Earth’s surface is about 700 W/m2. (a) Calculate the amount of energy that falls on a solar collector having an area of 0.500 m2 in 4.00 h. (b) What intensity would such sunlight have if concentrated by a magnifying glass onto an area 200 times smaller than its own?arrow_forwardNASA is giving serious consideration to the concept of solar sailing. A solar sailcraft uses a large, low-mass sail and the energy and momentum of sunlight for propulsion. (a) Should the sail be absorbing or reflective? Why? (b) The total power output of the sun is 3.9 x 1026 W. How large a sail is necessary to propel a 10,000 kg spacecraft against the gravitational force of the sun? Express your result in square kilometers. (c) Explain why your answer to part (b) is independent of the distance from the sun.arrow_forward
- Light with an intensity of (5.4x10^0) kW/m² falls normally on a surface and is completely reflected. What is the radiation pressure in μPa. Use two significant figures for your answer. Note: Your answer is assumed to be reduced to the highest power possible.arrow_forwardThe power radiated by the sun is 3.9 × 1026 W. The earth orbits the sun in a nearly circular orbit of radius 1.5 × 10¹¹ m. The earth's axis of rotation is tilted by 23.4° relative to the plane of the orbit (see the drawing), so sunlight does not strike the equator perpendicularly. What power strikes a 0.58-m² patch of flat land at the equator at point Q? Number Units Sunlight Axis of rotation Equator 23.4arrow_forwardCh 24, Problem 31 The power radiated by the sun is 3.9 × 1026 W. The earth orbits the sun in a nearly circular orbit of radius 1.5 × 1011 m. The earth's axis of rotation is tilted by 23.4° relative to the plane of the orbit (see the drawing), so sunlight does not strike the equator perpendicularly. What power strikes a 0.72-m2 patch of flat land at the equator at point Q?arrow_forward
- Physics for Scientists and Engineers: Foundations...PhysicsISBN:9781133939146Author:Katz, Debora M.Publisher:Cengage LearningPhysics for Scientists and Engineers, Technology ...PhysicsISBN:9781305116399Author:Raymond A. Serway, John W. JewettPublisher:Cengage LearningPrinciples of Physics: A Calculus-Based TextPhysicsISBN:9781133104261Author:Raymond A. Serway, John W. JewettPublisher:Cengage Learning