Q80 · Practice questionComplex familiar5 marks
QUESTION 80 (5 marks)
A spacecraft travels at from Earth to a star light-years away in the Earth frame. Ignore acceleration periods. Determine the travel time measured (a) on Earth and (b) by a clock on the spacecraft.
WORKED SOLUTION
5 marksPractice marking scheme
ANSWER
Earth: ; spacecraft: .
Worked solution
Earth frame:
At , . The spacecraft clock measures the proper time:
Equivalently, the spacecraft measures a contracted distance , giving .
Calculates Earth-frame travel time.
Calculates gamma.
Identifies spacecraft time as proper time.
Calculates spacecraft time.
Provides consistent interpretation.
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