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?
Trending nowThis is a popular solution!
Chapter 34 Solutions
EBK PHYSICS FOR SCIENTISTS AND ENGINEER
- The de-excitation of a state occurs by competing emission and relaxation processes. If the relaxation mechanisms are very effective:a) the emission of radiation is largeb) the emission of radiation is smallc) the emission occurs at a shorter wavelengthd) the de-excitation occurs only by emission processesarrow_forwardm C A block of mass m slides down a ramp of height hand collides with an identical block that is initially at rest. The two blocks stick together and travel around a loop of radius R without losing contact with the track. Point A is at the top of the loop, point B is at the end of a horizon- tal diameter, and point C is at the bottom of the loop, as shown in the figure above. Assume that friction between the track and blocks is negligible. (a) The dots below represent the two connected blocks at points A, B, and C. Draw free-body dia- grams showing and labeling the forces (not com ponents) exerted on the blocks at each position. Draw the relative lengths of all vectors to reflect the relative magnitude of the forces. Point A Point B Point C (b) For each of the following, derive an expression in terms of m, h, R, and fundamental constants. i. The speed of moving block at the bottom of the ramp, just before it contacts the stationary block ii. The speed of the two blocks immediately…arrow_forwardThe velocity of an elevator is given by the graph shown. Assume the positive direction is upward. Velocity (m/s) 3.0 2.5 2.0 1.5 1.0 0.5 0 0 5.0 10 15 20 25 Time (s) (a) Briefly describe the motion of the elevator. Justify your description with reference to the graph. (b) Assume the elevator starts from an initial position of y = 0 at t=0. Deriving any numerical values you need from the graph: i. Write an equation for the position as a function of time for the elevator from t=0 to t = 3.0 seconds. ii. Write an equation for the position as a function of time for the elevator from t = 3.0 seconds to t = 19 seconds. (c) A student of weight mg gets on the elevator and rides the elevator during the time interval shown in the graph. Consider the force of con- tact, F, between the floor and the student. How Justify your answer with reference to the graph does F compare to mg at the following times? and your equations above. i. = 1.0 s ii. = 10.0 sarrow_forward
- Students are asked to use circular motion to measure the coefficient of static friction between two materials. They have a round turntable with a surface made from one of the materials, for which they can vary the speed of rotation. They also have a small block of mass m made from the sec- ond material. A rough sketch of the apparatus is shown in the figure below. Additionally they have equipment normally found in a physics classroom. Axis m (a) Briefly describe a procedure that would allow you to use this apparatus to calculate the coefficient of static friction, u. (b) Based on your procedure, determine how to analyze the data collected to calculate the coefficient of friction. (c) One group of students collects the following data. r (m) fm (rev/s) 0.050 1.30 0.10 0.88 0.15 0.74 0.20 0.61 0.25 0.58 i. Use the empty spaces in the table as needed to calculate quantities that would allow you to use the slope of a line graph to calculate the coefficient of friction, providing labels with…arrow_forwardPART Aarrow_forwardanswer both questionarrow_forward
- Only part A.) of the questionarrow_forwardIn general it is best to conceptualize vectors as arrows in space, and then to make calculations with them using their components. (You must first specify a coordinate system in order to find the components of each arrow.) This problem gives you some practice with the components. Let vectors A = (1,0, -3), B = (-2, 5, 1), and C = (3,1,1). Calculate the following, and express your answers as ordered triplets of values separated by commas.arrow_forwardIn general it is best to conceptualize vectors as arrows in space, and then to make calculations with them using their components. (You must first specify a coordinate system in order to find the components of each arrow.) This problem gives you some practice with the components. Let vectors A = (1,0, −3), B = (-2, 5, 1), and C = (3,1,1). Calculate the following, and express your answers as ordered triplets of values separated by commas.arrow_forward
- Principles of Physics: A Calculus-Based TextPhysicsISBN:9781133104261Author:Raymond A. Serway, John W. JewettPublisher:Cengage LearningPhysics 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 Learning
- Glencoe Physics: Principles and Problems, Student...PhysicsISBN:9780078807213Author:Paul W. ZitzewitzPublisher:Glencoe/McGraw-HillUniversity Physics Volume 3PhysicsISBN:9781938168185Author:William Moebs, Jeff SannyPublisher:OpenStax