Question 19M.3.SL.TZ2.7a
| Date | May 2019 | Marks available | [Maximum mark: 1] | Reference code | 19M.3.SL.TZ2.7a |
| Level | SL | Paper | 3 | Time zone | TZ2 |
| Command term | Show | Question number | a | Adapted from | N/A |
A spaceship moves away from the Earth in the direction of a nearby planet. An observer on the Earth determines the planet is 4 ly from the Earth. The spacetime diagram for the Earth’s reference frame shows the worldline of the spaceship. Assume the clock on the Earth, the clock on the planet, and the clock on the spaceship were all synchronized when ct = 0.
Show, using the spacetime diagram, that the speed of the spaceship relative to the Earth is 0.80c.
[1]
Evidence of finding 1/gradient such as:
use of any correct coordinate pair to find v - eg or .
OR
measures tan of angle between ct and ct’ as about 39° AND tan 39 ≈ 0.8 ✔
Answer 0.8c given, so check coordinate values carefully.
Most candidates could show that the velocity of the spacecraft was 0.8c.
