Concept explainers
Tell It to the Judge. (a) How fast must you be approaching a red traffic light (λ = 675 nm) for it to appear yellow (λ = 575 nm)? Express your answer in terms of the
Want to see the full answer?
Check out a sample textbook solutionChapter 37 Solutions
University Physics with Modern Physics, Volume 2 (Chs. 21-37); Mastering Physics with Pearson eText -- ValuePack Access Card (14th Edition)
Additional Science Textbook Solutions
Physics for Scientists and Engineers with Modern Physics
Physics (5th Edition)
The Cosmic Perspective
Lecture- Tutorials for Introductory Astronomy
Applied Physics (11th Edition)
College Physics: A Strategic Approach (3rd Edition)
- Suppose an astronaut is moving relative to Earth at a significant fraction of the speed of light. (a) Does he observe the rate of his to have slowed? (b) What change in the rate of earthbound does he see? (c) Does his ship seem to him to shorten? (d) What about the distance between two stars that lie in the direction of his motion? (e) Do he and an earthbound observer agree on his velocity relative to Earth?arrow_forwardSuppose the primed and laboratory observers want to measure the length of a rod that rests on the ground horizontally in the space between the helicopter and the tower (Fig. 39.8B). To derive the length transformation L = L (Eq. 39.5), we had to assume that the positions of the two ends were determined simultaneously. What happens to the length transformation equation if both observers measure the end below the helicopter at one time t1 and the other end at a later time t2?arrow_forwardExplain why, when defining the length of a rod, it is necessary to specify that the positions of the ends of the rod are to be measured simultaneously.arrow_forward
- Suppose an astronaut is moving relative to the Earth at a significant fraction of the speed of light. (a) Does he observe the rate of his clocks to have slowed? (b) What change in the rate of Earth-bound clocks does he see? (c) Does his ship seem to him to shorten? (d) What about the distance between stars that lie on lines parallel to his motion? (e) Do he and an Earth-bound observer agree on his velocity relative to the Earth?arrow_forward(a) All but the closest galaxies are receding from our own Milky Way Galaxy. If a galaxy 12.0x109ly away is receding from us at 0.900c, at what velocity relative to us must we send an exploratory probe to approach the other galaxy at 0.990c as measured from that galaxy? (b) How long will it take the probe to reach the other galaxy as measured from Earth? You may assume that the velocity of the other galaxy remains constant. (c) How long will it then take for a radio signal to be beamed back? (All of this is possible in principle, but not practical.)arrow_forward(a) Find the value of for the following situation. An astronaut measures the length of his spaceship to be 100 m, while an observer measures it to be 25.0 m. (b) What is the of the spaceship relative to Earth?arrow_forward
- You are on the jury in a murder trial. Almost all the evidence points to the same defendant, but they have a seemingly airtight alibi: Exactly one hour before the murder, the accused drove a car through a radar checkpoint. Mr. Police Officer said that there was excellent visibility at the spot, so he had stood 6 meters from the road and measured the speed of the car when it was only 10 meters away from where he was standing. The radar2 showed 60 km/h, which was also the speed limit at the location, so the car was allowed to continue. Thorough technical investigations show that the car continued at the same constant speed for the next hour. The murder occurred 70km away from the checkpoint, so it appears that the accused could not have arrived in time to commit the murder. Show using related rates that the actual speed of the car in the radar check was over 70 km/h and that the defendant therefore had time to commit the murder.arrow_forwardYou have an assistantship with a math professor in a future world where space travel is common and spacecraft regularly achieve near-light speeds. A spacecraft has taken off recently to carry individuals to colonize an Earth-like planet around a nearby star. Your professor, who remains on Earth,is teaching the students on the spacecraft via the future version of distance learning. It is time for the students on the spacecraft to take a math exam. The professor wishes the students to have a time interval Δtp = 2.00 h to complete the exam, so just as the spacecraft passes Earth on its last triparound the Sun at its constant cruising speed of 0.960c, she sends a signal to the proctor to have the students begin the exam. Knowing of your experience in physics courses, the professor asks you to determine the time interval through which she should wait before sending a radio signal to thedeparting spacecraft to tell the proctor to have the students stop working on the exam.arrow_forwardYou are on an interstellar mission from the Earth to the 8.7 light-years distant star Sirius. Your spaceship can travel with 70% the speed of light and has a cylindrical shape with a diameter of 6 m at the front surface and a length of 25 m. You have to cross the interstellar medium with anthe approximated density of 1 hydrogen atom/m3Because you are moving at an enormous speed, your mission from the previous part will be influenced by the effects of time dilation described by special relativity: Your spaceshiplaunches in June 2020 and returns back to Earth directly after arriving at Sirius.(a) How many years will have passed from your perspective?(b) At which Earth date (year and month) will you arrive back to Earth?arrow_forward
- (a) How long in seconds does it take a radio signal to travel 180 km from a transmitter to a receiving antenna? (b) We see a full Moon by reflected sunlight. How much earlier did the light that enters our eye leave the Sun? The Earth – Moon and Earth – Sun distances are 3.8x105 km and 1.5 × 108 km, respectively. (c) What is the round-trip travel time in seconds for light between Earth and a spaceship at a 6.8 × 107 km distance from Earth? (d) Suppose astronomers observe a supernova about 7300 light-years (ly) distant. How long ago in years did the explosion actually occur?arrow_forward(a) In communicating with an astronaut on the moon, 3.8 x 108 m from earth, what is the minimum time delay in getting a response to a question? (b) What would the minimum time delay be for communication with an astronaut at a distance of 2 light-years from earth?arrow_forward(a) How long in seconds does it take a radio signal to travel 180 km from a transmitter to a receiving antenna? (b) We see a full Moon by reflected sunlight. How much earlier did the light that enters our eye leave the Sun? The Earth - Moon and Earth - Sun distances are 3.8x105 km and 1.5 x 108 km, respectively. (c) What is the round-trip travel time in seconds for light between Earth and a spaceship at a 9.0 x 106 km distance from Earth? (d) Suppose astronomers observe a supernova about 7600 light-years (ly) distant. How long ago in years did the explosion actually occur? (a) Number Units (b) Number Units (c) Number Units (d) Number Unitsarrow_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 LearningUniversity Physics Volume 3PhysicsISBN:9781938168185Author:William Moebs, Jeff SannyPublisher:OpenStax
- College PhysicsPhysicsISBN:9781938168000Author:Paul Peter Urone, Roger HinrichsPublisher:OpenStax College