MYP Physics · 16 · data analysis
One spectral line shifts unusually far
Space physics · Original GioPhysics question with a detailed, mark-by-mark answer guide.
- Demand
- demanding
- Marks
- 8
- Topics
- 2
- Answer
- Complete
Question8 marks
The same spectral feature has laboratory wavelength 500 nm. Four galaxies give (distance in Mpc, observed wavelength in nm): (10, 501), (20, 502), (30, 505), (40, 504). Mpc is a distance unit; no conversion is needed. For these small shifts, use z = (observed wavelength − laboratory wavelength)/laboratory wavelength and recession speed v ≈ cz, with c = 300000 km/s. Calculate each speed and v/d. Test whether v is proportional to distance using agreement within 5% of the first v/d as the classroom rule. Explain what the pattern can establish and one limitation.
Task interpretation
What a complete response should do
Identify the useful evidence, process it with units, and make only the conclusion the data supports.
Split the problem into linked stages and state why each relationship applies.
- Response type
- data analysis
- Allocation
- 8 marks
- Demand
- demanding
Galaxy spectral measurements
Observed wavelengths plotted against the supplied independent distance estimates.
Read the exact data as a table
| Distance (Mpc) | Observed wavelength (nm) |
|---|---|
| 10 | 501 |
| 20 | 502 |
| 30 | 505 |
| 40 | 504 |
These are the supplied readings, not a worked answer. No fitted trend is drawn.
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