Question 18M.3.SL.TZ2.5
| Date | May 2018 | Marks available | [Maximum mark: 5] | Reference code | 18M.3.SL.TZ2.5 |
| Level | SL | Paper | 3 | Time zone | TZ2 |
| Command term | Calculate, Determine, Explain, Outline | Question number | 5 | Adapted from | N/A |
Explain what is meant by the statement that the spacetime interval is an invariant quantity.
[1]
quantity that is the same/constant in all inertial frames
[1 mark]
Observer A detects the creation (event 1) and decay (event 2) of a nuclear particle. After creation, the particle moves at a constant speed relative to A. As measured by A, the distance between the events is 15 m and the time between the events is 9.0 × 10–8 s.
Observer B moves with the particle.
For event 1 and event 2,
calculate the spacetime interval.
[1]
spacetime interval = 272 – 152 = 504 «m2»
[1 mark]
determine the time between them according to observer B.
[2]
ALTERNATIVE 1
Evidence of x′ = 0
t′ «» = 7.5 × 10–8 «s»
ALTERNATIVE 2
γ = 1.2
t′ «= » = 7.5 × 10–8 «s»
[2 marks]
Outline why the observed times are different for A and B.
[1]
observer B measures the proper time and this is the shortest time measured
OR
time dilation occurs «for B's journey» according to A
OR
observer B is stationary relative to the particle, observer A is not
[1 mark]