A physics professor on Earth gives an exam to her students who are on a spaceship traveling at speed v relative to Earth. The moment the ship passes the professor, she signals the start of the exam. If she wishes her students to have time T0 (spaceship time) to complete the exam, show that she should wait a time (Earth time) of
before sending a light signal telling them to stop. (Hint: Remember that it takes some time for the second light signal to travel from the professor to the students.)
Want to see the full answer?
Check out a sample textbook solutionChapter 1 Solutions
Modern Physics
- Joe and Moe are twins. In the laboratory frame at location S1 (2.00 km, 0.200 km, 0.150 km). Joe shoots a picture for aduration of t= 12.0 s. For the same duration as measured inthe laboratory frame, at location S2 (1.00 km, 0.200 km,0.300 km), Moe also shoots a picture. Both Joe and Moe begintaking their pictures at t = 0 in the laboratory frame. Determine the duration of each event as measured by an observer ina frame moving at a speed of 2.00 108 m/s along the x axisin the positive x direction. Assume that at t = t = 0, the origins of the two frames coincide.arrow_forwardIf two spaceships are heading directly toward each other at 0.800c, at what speed must a canister be shot from the first ship to approach the other at 0.999c as seen by the second ship?arrow_forwardTwo spaceships approach each other, each moving with the same speed as measured by an observer on the Earth. If their relative speed is 0.70c, what is the speed of each spaceship?arrow_forward
- A spaceship in the shape of a sphere moves past an observer on Earth with a speed of 0.5c. What shape will the observer see as the spaceship moves past?arrow_forwardGive a physical argument showing that it is impossible to accelerate an object of mass m to the speed of light, even with a continuous force acting on it.arrow_forwardAn astronaut is traveling in a spacecraft in outer space in a straight line at a constant speed of 0.500c. Which of the following effects would she experience? (a) She would feel heavier. (b) She would find it harder to breathe. (c) Her heart rate would change. (d) Some of the dimensions of her spacecraft would be shorter. (e) None of those answers is correct.arrow_forward
- An electron has a speed of 0.75c. Find the speed of a proton that has (a) the same kinetic energy as the electron and (b) the same momentum as the electron.arrow_forwardAn observer in reference frame S sees two events as simultaneous. Event A occurs at the point (50.0 m, 0, 0) at the instant 9:00:00 Universal time, 15 January 2001. Event B occurs at the point (150 m, 0, 0) at the same moment. A second observer, moving past with a velocity of , also observes the two events. In her reference frame S′, which event occurred first and what time elapsed between the events?arrow_forward(a) Show that (pc)2/(m c 2)2=21. This means that at large velocities pcmc2. (b) Is Epc when =30.0, as for the astronaut discussed in the twin paradox?arrow_forward
- What is the momentum of an electron travelling at 0.98c?arrow_forwardAn object having mass of 900 kg and traveling at a speed of 0.850c collides with a stationary object having mass 1400 kg. The two objects stick together. Find (a) the speed and (b) the mass of the composite object.arrow_forwardWhen a missile is shot from one spaceship toward another, it leaves the first at 0.950c and approaches the other at 0.750c. What is the relative velocity of the two ships?arrow_forward
- Principles of Physics: A Calculus-Based TextPhysicsISBN:9781133104261Author:Raymond A. Serway, John W. JewettPublisher:Cengage LearningModern PhysicsPhysicsISBN:9781111794378Author:Raymond A. Serway, Clement J. Moses, Curt A. MoyerPublisher:Cengage LearningPhysics for Scientists and Engineers: Foundations...PhysicsISBN:9781133939146Author:Katz, Debora M.Publisher:Cengage Learning
- Physics for Scientists and Engineers, Technology ...PhysicsISBN:9781305116399Author:Raymond A. Serway, John W. JewettPublisher:Cengage LearningUniversity Physics Volume 3PhysicsISBN:9781938168185Author:William Moebs, Jeff SannyPublisher:OpenStaxClassical Dynamics of Particles and SystemsPhysicsISBN:9780534408961Author:Stephen T. Thornton, Jerry B. MarionPublisher:Cengage Learning