Q267 · Practice questionSimple familiar1 mark
QUESTION 267
A spacecraft passes station A and later station B. The two stations are at rest relative to each other and their clocks are synchronised in their own frame. A single spacecraft clock records both passages. Which interval is the proper time between these passage events?
(A)
The interval on the spacecraft clock, since both events occur at that clock.
(B)
The interval from the station clocks, since they are synchronised.
(C)
Both intervals, since both sets of clocks are accurate.
(D)
Neither interval, since one event is at A and the other at B.
WORKED SOLUTION
1 markAnswer A
ANSWER
A. The interval on the spacecraft clock, since both events occur at that clock.
Worked solution
Proper time is measured in the frame in which both events occur at the same spatial location. The same moving clock is present at each passage. Their locations differ in the station frame.
Equivalent physically justified methods, alternative valid sketches and consistent units accepted.
Accept sensible significant figures and consistent rounding from stated constants.
Select A.
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