DP Physics (last assessment 2024)
Question 18M.3.SL.TZ2.4c
| 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 « =» 4000 «s»
total time «= 67.5 + 112.5» = 180 minutes or 3.00 h or 3:00am
[2 marks]
