Questions
Question 1
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What is proper time?
Question 2
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State the time dilation formula.
Question 3
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Which interval is shorter: proper time \(\Delta\tau\) or dilated time \(\Delta t\)?
Question 4
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A moving clock has proper tick interval \(2.00\,\mathrm{ns}\). If \(\gamma=3.00\), what interval is measured in the lab?
Question 5
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A particle moves at \(0.800c\). Find \(\gamma\).
Question 6
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A spacecraft clock measures \(10.0\,\mathrm s\) between two events on board. The spacecraft moves with \(\gamma=1.25\) relative to Earth. What time interval does Earth measure?
Question 7
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A muon has proper lifetime \(2.20\,\mu\mathrm s\) and moves with \(\gamma=10.0\). Find its mean lifetime in the laboratory.
Question 8
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A clock moving at \(0.600c\) measures \(4.00\,\mathrm s\). Find the interval measured by a stationary lab observer.
Question 9
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A lab measures a moving particle lifetime of \(8.00\,\mu\mathrm s\). If \(\gamma=4.00\), find the proper lifetime.
Question 10
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A muon moves at \(0.995c\) and has proper lifetime \(2.20\,\mu\mathrm s\). Estimate the distance it travels in the lab during one mean lifetime.
Question 11
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At what speed does a moving clock run slow by a factor of \(2.00\) compared with the lab?
Question 12
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An astronaut ages \(3.00\) years during a trip. Earth measures \(5.00\) years for the same departure-arrival events. Find \(\gamma\) and the ship speed.
Question 13
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A particle travels \(1.50\,\mathrm{km}\) in the lab at \(0.900c\). Find the proper time elapsed on the particle.
Question 14
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Why is the proper time between two ticks of a moving clock measured in the clock's own frame?
Question 15
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A clock's moving-frame interval is \(12.0\,\mathrm{ns}\), and its proper interval is \(5.00\,\mathrm{ns}\). Is this possible? If so, find the speed.
Question 16
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Derive time dilation from the Lorentz time transformation for two events at the same place in \(S'\).
Question 17
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A student uses \(\Delta t=\Delta\tau/\gamma\) and gets a lab lifetime smaller than the particle lifetime. Identify the error.
Question 18
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Explain how muons produced high in the atmosphere can reach Earth's surface using time dilation.
Question 19
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Why is it incomplete to say simply "moving clocks run slow" without naming a frame?
Question 20
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Show that time dilation disappears in the Newtonian limit.