Q211 · Practice questionSimple familiar1 mark
QUESTION 211
A spacecraft observer measures the interval between two events. Which condition makes that measured interval the proper time interval between those events?
(A)
The events are simultaneous in the ground frame.
(B)
The spacecraft moves at constant velocity.
(C)
The events occur at opposite ends of the spacecraft.
(D)
The events occur at the same position in the spacecraft frame.
WORKED SOLUTION
1 markAnswer D
ANSWER
D. The events occur at the same position in the spacecraft frame.
Worked solution
Proper time is measured in a frame in which the two events occur at the same spatial position, allowing one clock to record both. Inertial motion alone does not establish that condition.
Equivalent physically justified methods and consistent equivalent units accepted.
Displayed decimals are model answers; accept appropriate significant figures and consistent rounding from stated constants.
Select D.
Practice question aligned to the current QCAA syllabus; review the worked solution and marking criteria.
View the QCAA syllabus