Chapter 33: Problem 6
If you're in a spaceship moving at \(0.95 c\) relative to Earth, do you perceive time to be passing more slowly than it would on Earth? Think! Is your answer consistent with the relativity principle?
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Chapter 33: Problem 6
If you're in a spaceship moving at \(0.95 c\) relative to Earth, do you perceive time to be passing more slowly than it would on Earth? Think! Is your answer consistent with the relativity principle?
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The Curiosity rover touched down on Mars when Earth and Mars were 14 light- minutes apart. At the instant of touchdown, clocks at Mission Control in Pasadena, California, read 10: 31 PM. As judged by observers on a spacecraft heading along the Earth Mars line at \(0.35 c,\) did touchdown occur before or after the time the clocks in Pasadena read \(10: 31 \mathrm{PM}\), and by how much?
An extraterrestrial spacecraft whizzes through the solar system at \(0.80 c .\) How long does it take to go the 8.3 light-minute-distance from Earth to Sun (a) according to an observer on Earth and (b) according to an alien aboard the ship?
Consider a line of positive charge with line charge density \(\lambda\) as measured in a frame \(S\) at rest with respect to the charges. (a) Show that the electric field a distance \(r\) from this charged line has magnitude \(E=\lambda / 2 \pi \epsilon_{0} r,\) and that there's no magnetic field (no relativity needed here). Now consider the situation in a frame \(S^{\prime}\) moving at speed \(v\) parallel to the line of charge. (b) Show that the charge density measured in \(S^{\prime}\) is given by \(\lambda^{\prime}=\gamma \lambda\), where \(\gamma=1 / \sqrt{1-v^{2} / c^{2}},\) (c) Use the result of (b) to find the electric field in \(S^{\prime}\). since the charge is moving with respect to \(S^{\prime}\), there's a current in \(S^{\prime}\), (d) Find an expression for this current and (e) for the magnetic field it produces. Determine the values of the quantities ( \(f\) ) \(\vec{E} \cdot \vec{B}\) and \((g) E^{2}-c^{2} B^{2}\) in both reference frames, and show that these quantities are invariant. Your result gives a hint at how electric and magnetic fields transform, and demonstrates one instance of the fact that \(\vec{E} \cdot \vec{B}\) and \(E^{2}-c^{2} B^{2}\) are always invariant.
The rest energy of an electron is \(511 \mathrm{keV}\). What's the approximate speed of an electron whose total energy is \(1 \mathrm{GeV} ?\) (Note: No calculations needed!)
Two stars are 50 ly apart, measured in their common rest frame. How far apart are they to a spaceship moving between them at \(0.75 c ?\)
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