Question 19M.3.HL.TZ2.9
| Date | May 2019 | Marks available | [Maximum mark: 5] | Reference code | 19M.3.HL.TZ2.9 |
| Level | HL | Paper | 3 | Time zone | TZ2 |
| Command term | Calculate, Explain | Question number | 9 | Adapted from | N/A |
A rocket is accelerating upwards at 9.8 m s-2 in deep space. A photon of energy 14.4 keV is emitted upwards from the bottom of the rocket and travels to a detector in the tip of the rocket 52.0 m above.
Explain why a change in frequency is expected for the photon detected at the top of the rocket.
[3]
ALTERNATIVE 1
detector accelerates/moves away from point of photon emission ✔
so Doppler effect / redshift ✔
so f decreases ✔
ALTERNATIVE 2
equivalent to stationary rocket on earth’s surface ✔
photons lose «gravitational» energy as they move upwards ✔
h f OR f decreases ✔
Most candidates answered this question correctly using the equivalence principle and could show that the frequency would decrease.
Calculate the frequency change.
[2]
Arithmetic mistakes were common at the different stages of the calculations even when the process used was correct.