Question 19M.3.SL.TZ1.4b
| Date | May 2019 | Marks available | [Maximum mark: 2] | Reference code | 19M.3.SL.TZ1.4b |
| Level | SL | Paper | 3 | Time zone | TZ1 |
| Command term | Demonstrate | Question number | b | Adapted from | N/A |
Muons are created at a height of 3230 m above the Earth’s surface. The muons move vertically downward at a speed of 0.980 c relative to the Earth’s surface. The gamma factor for this speed is 5.00. The half-life of a muon in its rest frame is 2.20 μs.
Demonstrate how an observer moving with the same velocity as the muons accounts for the answer to (a)(ii).
[2]
observer measures the distance to the surface to be shorter «by a factor of 5.0»/ length contraction occurs ✔
so time of travel again corresponds to «»= 1.0 half-life ✔
Some candidates struggled in b), with only the best candidates identified length contraction. Importantly, the command term here is “demonstrate” which means students must make their response clear by reasoning or evidence. Many who identified length contraction did not provide adequate reasoning to gain full marks.
