Chapter 5: Problem 49
What is the relative velocity of two spaceships if one fires a missile at the other at \(0.750 c\) and the other observes it to approach at \(0.950 c ?\)
Chapter 5: Problem 49
What is the relative velocity of two spaceships if one fires a missile at the other at \(0.750 c\) and the other observes it to approach at \(0.950 c ?\)
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Get started for freeShow that for any relative velocity \(v\) between two observers, a beam of light projected by one directly away from the other will move away at the speed of light (provided that \(v\) is less than \(c,\) of course).
What is \(\gamma\) for a proton having a mass energy of 938.3 MeV accelerated through an effective potential of \(1.0 \mathrm{TV}\) (teravolt)?
(a) Suppose the speed of light were only \(3000 \mathrm{m} / \mathrm{s}\). A jet fighter moving toward a target on the ground at 800 \(\mathrm{m} / \mathrm{s}\) shoots bullets, each having a muzzle velocity of 1000 \(\mathrm{m} / \mathrm{s} .\) What are the bullets' velocity relative to the target? (b) If the speed of light was this small, would you observe relativistic effects in everyday life? Discuss.
A highway patrol officer uses a device that measures the speed of vehicles by bouncing radar off them and measuring the Doppler shift. The outgoing radar has a frequency of \(100 \mathrm{GHz}\) and the returning echo has a frequency \(15.0 \mathrm{kHz}\) higher. What is the velocity of the vehicle? Note that there are two Doppler shifts in echoes. Be certain not to round off until the end of the problem, because the effect is small.
(a) All but the closest galaxies are receding from our own Milky Way Galaxy. If a galaxy \(12.0 \times 10^{9}\) ly away is receding from us at \(0.900 c,\) at what velocity relative to us must we send an exploratory probe to approach the other galaxy at \(0.990 c\) 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.)
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