| Date | May 2018 | Marks available | 1 | Reference code | 18M.3.SL.TZ2.3 |
| Level | Standard level | Paper | Paper 3 | Time zone | Time zone 2 |
| Command term | Calculate | Question number | 3 | Adapted from | N/A |
Question
Rocket A and rocket B are travelling in opposite directions from the Earth along the same straight line.
In the reference frame of the Earth, the speed of rocket A is 0.75c and the speed of rocket B is 0.50c.
Calculate, for the reference frame of rocket A, the speed of rocket B according to the Galilean transformation.
Calculate, for the reference frame of rocket A, the speed of rocket B according to the Lorentz transformation.
Outline, with reference to special relativity, which of your calculations in (a) is more likely to be valid.
Markscheme
1.25c
[1 mark]
ALTERNATIVE 1
\(u' = \frac{{(0.50 + 0.75)}}{{1 + 0.5 \times 0.75}}c\)
0.91c
ALTERNATIVE 2
\(u' = \frac{{ - 0.50 - 0.75}}{{1 - ( - 0.5 \times 0.75)}}c\)
–0.91c
[2 marks]
nothing can travel faster than the speed of light (therefore (a)(ii) is the valid answer)
OWTTE
[1 mark]
