Question 19M.3.SL.TZ1.5b
| Date | May 2019 | Marks available | [Maximum mark: 2] | Reference code | 19M.3.SL.TZ1.5b |
| Level | SL | Paper | 3 | Time zone | TZ1 |
| Command term | Suggest | Question number | b | Adapted from | N/A |
The diagram shows space and time axes and ct for an observer at rest with respect to a galaxy. A spacecraft moving through the galaxy has space and time axes ′ and ct′.
A rocket is launched towards the right from the spacecraft when it is at the origin of the axes. This is labelled event 1 on the spacetime diagram. Event 2 is an asteroid exploding at = 100 ly and ct = 20 ly.
Suggest whether the rocket launched by the spacecraft might be the cause of the explosion of the asteroid.
[2]
ALTERNATIVE 1
the rocket would have to travel faster than the speed of light ✔
so impossible ✔
ALTERNATIVE 2
drawing of future lightcone at origin ✔
and seeing that the asteroid explodes outside the lightcone so impossible ✔
ALTERNATIVE 3
the event was observed at +20 years, but its distance (stationary) is 100 ly ✔
so the asteroid event happened 80 years before t = 0 for the galactic observer ✔
Most of the candidates identified, that the spacecraft was launched after the asteroid explosion and better candidates were also able to explain their reasoning with a drawing of light cones on the spacetime graph being the most popular response type.
