Question 19M.3.SL.TZ1.5c
| Date | May 2019 | Marks available | [Maximum mark: 1] | Reference code | 19M.3.SL.TZ1.5c |
| Level | SL | Paper | 3 | Time zone | TZ1 |
| Command term | Show that | Question number | c | 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.
Show that the value of the invariant spacetime interval between events 1 and 2 is 9600 ly2.
[1]
1002 − 202 = 9600 «ly2» ✔
Also accept 98 (the square root of 9600).
Allow negative value.
Most of the candidates well used the formula for invariant spacetime from the data booklet, but only a few strong candidates were able to determine the time between the events according to the spacecraft observer. This implies a lack of understanding of the concept of invariance for different frames of reference.
