A ground-based observer measures a rocket ship to have a length of 120 m. If the rocket was traveling at 89% of the speed of light when the measurement was made, what length would the rocket have if brought to rest? m Additional Materials eBook Viewing Saved Work Revert to Last Response

A neutron lives 900 s when at rest relative to an observer. How fast is the neutron moving relative to an observer who measures its life span to be 2065 s?

A clock in a spaceship tuns one-tenth the rate at which an identical clock on Earth runs. What is the speed of the spaceship?

Particles called -mesons are produced by accelerator beams. If these particles travel at 2.70108 m/s and live 2.60108 s when at rest relative to an observer, how long do they live as viewed in the laboratory?

. If the relativistic kinetic energy of a particle is 9 times its rest energy, at what fraction of the speed of light must the particle be traveling?

Check Your Understanding a. A particle travels at 1.90108m/sand lives 2.10108swhen at rest relative to an observer. How long does the particle live as viewed in the laboratory? b. Space craft A and B pass in opposite directions at a relative speed of 4.00107m/s . An internal clock in space craft A causes it to emit a radio signal for 1.00 s. The computer in spacecraft B corrects for the beginning and end of the signal having traveled different distances, to calculate the time interval during which ship A was emitting the signal. What is the time interval that the computer in spacecraft B calculates?

Same two observers as in the preceding exercise, but now we look at two events occurring in spaceship A. A photon arrives at the origin of A at its time and another photon arrives atat in the frame of ship A. (a) Find the coordinates and times of the two events as seen by an observer in frame B. (b) In which frame are the two events simultaneous and in which frame are they are not simultaneous?

What is the velocity of an electron that has a momentum of 3.04×10-21?kg·m/s? Note that you must calculate the velocity to at least four digits to see the difference from c.

One cosmic ray neuron has a velocity of 0.250c relative to the Earth. (a) What is the neutron's total energy in MeV? (b) Find its momentum. (c) Is in this situation? Discuss in terms of the equation given in part (a) of the previous problem.

(a) All but the closest galaxies are receding from our own Milky Way Galaxy. If a galaxy 12.0109ly ly away is receding from us at 0. 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 the 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.)