Q9 · 2024 · Paper 1Complex familiar1 mark
QUESTION 9
A passenger at the centre of a train moving at a relativistic speed switches on a light. According to the passenger, light travels outwards as shown.
How would a stationary observer, watching the train pass by them, record this event?
(A)
Light will reach the back of the train first.
(B)
Light will reach the front of the train first.
(C)
Light will reach both ends of the train at t0.
(D)
Light will reach both ends of the train simultaneously.
WORKED SOLUTION
1 markAnswer A
ANSWER
A
Worked solution
For the ground observer the back of the train moves toward the backward-travelling light while the front moves away from the forward-travelling light, so the back is reached first. Option A.
Selects option A.
Worked explanation by QCE Vault; correct option verified against the QCAA answer key.