Date | November 2017 | Marks available | 2 | Reference code | 17N.2.SL.TZ0.5 |
Level | Standard level | Paper | Paper 2 | Time zone | Time zone 0 |
Command term | Determine | Question number | 5 | Adapted from | N/A |
Question
A satellite powered by solar cells directed towards the Sun is in a polar orbit about the Earth.
The satellite is orbiting the Earth at a distance of 6600 km from the centre of the Earth.
The satellite carries an experiment that measures the peak wavelength emitted by different objects. The Sun emits radiation that has a peak wavelength λS of 509 nm. The peak wavelength λE of the radiation emitted by the Earth is 10.1 μm.
Determine the orbital period for the satellite.
Mass of Earth = 6.0 x 1024 kg
Determine the mean temperature of the Earth.
Suggest how the difference between λS and λE helps to account for the greenhouse effect.
Not all scientists agree that global warming is caused by the activities of man.
Outline how scientists try to ensure agreement on a scientific issue.
Markscheme
\(\frac{{m{v^2}}}{r} = G\frac{{Mm}}{{{r^2}}}\)
leading to T2 = \(\frac{{4{\pi ^2}{r^3}}}{{GM}}\)
T = 5320 «s»
Alternative 2
«\(v = \sqrt {\frac{{G{M_E}}}{r}} \)» = \(\sqrt {\frac{{6.67 \times {{10}^{ - 11}} \times 6.0 \times {{10}^{24}}}}{{6600 \times {{10}^3}}}} \) or 7800 «ms–1»
distance = 2\(\pi \)r = 2\(\pi \) x 6600 x 103 «m» or 4.15 x 107 «m»
«T = \(\frac{d}{v} = \frac{{4.15 \times {{10}^7}}}{{7800}}\)» = 5300 «s»
Accept use of ω instead of v
T = «\(\frac{{2.90 \times {{10}^{ - 3}}}}{{{\lambda _{{\text{max}}}}}} = \)» \(\frac{{2.90 \times {{10}^{ - 3}}}}{{10.1 \times {{10}^{ - 6}}}}\)
= 287 «K» or 14 «°C»
Award [0] for any use of wavelength from Sun
Do not accept 287 °C
wavelength of radiation from the Sun is shorter than that emitted from Earth «and is not absorbed by the atmosphere»
infrared radiation emitted from Earth is absorbed by greenhouse gases in the atmosphere
this radiation is re-emitted in all directions «including back to Earth»
peer review
international collaboration
full details of experiments published so that experiments can repeated
[Max 1 Mark]