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Question 18M.3.SL.TZ2.4c

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Date May 2018 Marks available [Maximum mark: 2] Reference code 18M.3.SL.TZ2.4c
Level SL Paper 3 Time zone TZ2
Command term Determine Question number c Adapted from N/A
c.
[Maximum mark: 2]
18M.3.SL.TZ2.4c

When a spaceship passes the Earth, an observer on the Earth and an observer on the spaceship both start clocks. The initial time on both clocks is 12 midnight. The spaceship is travelling at a constant velocity with γ = 1.25. A space station is stationary relative to the Earth and carries clocks that also read Earth time.

(c)

As the spaceship passes the space station, the space station sends a radio signal back to the Earth. The reception of this signal at the Earth is event A. Determine the time on the Earth clock when event A occurs.

[2]

Markscheme

signal will take «112.5 × 0.60 =» 67.5 «minutes» to reach Earth «as it travels at c»

OR

signal will take « 1.2 × 10 12 3 × 10 8 =» 4000 «s»

 

total time «= 67.5 + 112.5» = 180 minutes or 3.00 h or 3:00am

 

[2 marks]