(b) total power required = ( =)360kW; 1

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1 1. (a) solar energy to thermal/internal energy ; Do not accept light/heat. (b) total power required = ( =)360kW; input power = 2000 kw; area = m 2 ; Award [2 max] if calculation is f one house only (25.8 m 2 ). (c) no/little power at night; power fluctuates accding to weather conditions/cloud; seasonal changes; very large surface area required; Any other sensible physical reason. Do not allow low efficiency unless compared to other devices. Do not allow cost expense. 2 max [6] 2. (a) thermal energy transferred to the surroundings / energy that is converted to thermal energy; that is no longer available to produce useful wk / OWTTE; 2 (b) (i) the energy/power available from the (combustion of the) coal; 1 A hot gases from burning of coal/into chimney; B radiation and convection from the boiler; C friction at the bearings/in the mechanism of the dynamo; 3 [6] 3. (a) enrichment; 1 IB Questionbank Physics 1

2 24 (b) power produced = 75 MW; 0.32 energy produced in a year ( =) J; number of reactions required in one year 11 = ; mass used ( ) 29kg mass used = 29kg; (c) the neutrons would not be slowed down; therefe they would not be/have less chance of being captured/induce fission; so (much) less/no power would be produced; 3 (d) (i) beta decay; 1 the reactions end up producing plutonium (from uranium 238); (this isotope of) plutonium may be used to manufacture nuclear weapons / can be used as fuel in other reacts / plutonium is extremely toxic; the products of the reactions are radioactive f long periods of time / OWTTE; therefe posing stage/safety problems; 2 [11] 4. (a) the solar radiation is captured by a disc of area πr 2 where R is the radius of the Earth; but is distributed (when averaged) over the entire Earth s surface which has an area four times as large; Award [1] f reference to absption/reflection. (b) (i) 0.700; 1 I(= eσt a 4 ) = ; = 136 W m 2 1 IB Questionbank Physics 2

3 (iii) σt e 4 = Wm 2 ; hence T e = 286K; 2 (c) (i) the Earth radiates radiation in the infrared region of the spectrum; the greenhouse gases have energy level differences (in their molecular energy levels) cresponding to infrared energies; and so the infrared photons are absbed; the Earth radiates photons of infrared frequency; the greenhouse gas molecules oscillate/vibrate with frequencies in the infraredregion; and so because of resonance the photons are absbed; 3 most incoming radiation consists of photons in the visible/ ultraviolet region / photons of much shter wavelength than those radiated by the Earth / photons of different wavelength of that radiated by Earth; and so these cannot be absbed; 2 (iii) Source: emissions from volcanoes / burning of fossil fuels in power plants/cars / breathing; Sink: oceans / rivers / lakes / seas / trees; 2 [13] 5. (a) energy emitted per unit time / power per unit area; proptional to [absolute temperature/temperature in K] 4 ; 2 Must define symbols if used. (b) (i) power = π [ ] ; = W 2 26 incident area ; 11 2 area 4π[ ] = 1400 W m 2 ; 2 (iii) (albedo of Earth means) some radiation is reflected; Earth s surface is not always nmal to incident radiation; some energy lost as radiation travels to Earth; 2 max IB Questionbank Physics 3

4 (iv) power absbed = power radiated; uses 5.67 l = to yield answer close to 240 / evaluates ; 2 (c) radiation from the Sun is re-emitted at longer wavelengths; (longer radiation) wavelengths are absbed by greenhouse gases; some radiation re-emitted back to Earth; 3 (d) me CO 2 /named greenhouse gas released into atmosphere; enhanced greenhouse effect; because me re-radiation of energy towards surface; 3 [15] 6. (a) (i) 3; 1 m = [ ]; = 0.186(u); energy released = = 173(MeV) ; ; (= 2.768) (J) 4 m = [ ]; = 0.186(u); mass converted= (= ); (use of E = mc 2 ) energy = ; (= 2.77) (J) Award [2 max] if mass difference is increct. Award [3 max] if the candidate uses a value f x inconsistent with (a)(i). (iii) greater/higher energy; 1 (b) reduces neutron speed to (thermal) lower speeds; so that chance of initiating fission is higher; 2 Accept fast neutrons cannot cause fission f 2nd marking point. IB Questionbank Physics 4

5 (c) 40 % efficient so 40 (MW) required; = per second; number of fissions per day = ; = 48 g per day; [12] 7. (a) (i) source of energy (in a useful fm); 1 Award any two of the following. peat; coal; oil; gas; Do not accept derived fuels, e.g. diesel. 2 max (iii) rate of production of fuel much smaller than rate of usage; so fuel will be exhausted/run out; 2 (iv) idea that width of arrow is related to magnitude of energy/power; 1.0 efficiency = = Allow any efficiency i.e. ±0.1cm on each measurement. Allow answer expressed as percentage. 2 (b) e.g. high energy density; readily available (in sht-term); cheaper production of electrical energy; health considerations not treated as a maj issue; not possible to generate sufficient electrical energy without it; many transpt systems rely on fossil fuels; power stations can be built close to energy source; These marking points are not an exhaustive list. Do not allow repetitions vague statements they should be clear and precise. 3 max [10] 8. (a) the molecules of the gas have a natural frequency of oscillation equal to the frequency of infra-red; (the molecule will absb radiation) because of resonance at this (resonant) frequency; 2 (b) because it traps/absbs infra-red radiated by the surface of Earth; 1 IB Questionbank Physics 5

6 (c) nitrogen dioxide / methane / water / NO 2 / CH 4 / H 2 O; 1 (d) (i) (most of the) infra-red (radiation) absbed is not all re-radiated into space/escaping into space / OWTTE; 1 reflectedelectromagneticradiation albedo = / measure of the incident electromagneticradioation amount of radiation reflected into space; carbon dioxide reduces the amount of reflected radiation; hence albedo decreased; 3 Award [0] f a bald answer in terms of albedo decreased. (e) present I I out in = 0.30 so present I out = 102 (W m 2 ); after doubling new I out = ( ) = 98.6(W m 2 ); change = ; ( 3 W m 2 ) 3 Accept wking from 0.31 to (f) assume all the radiated energy is in the infra-red / all the extra gas absbs the radiated radiation / no change in radiated power due to Earth temperature change; 1 [12] 9. (a) (i) mass = ; loss in gpe = ; Accept use of 335 m (including centre of mass of tank water) accept g = (J); (J) 3 Do not penalize if the first marking point is incpated into the second marking point. flows f 6250 s; W W; Accept solution from (a)(i) from flow rate. (b) (i) 53%; 1 IB Questionbank Physics 6

7 losses in crect der and approximately crect ratio of size; arrows crectly labelled with source of loss; 2 Labelling of width in % is acceptable f crect ratio only. (diagram not to scale) (c) (i) transmit at high/increased potential difference/voltage; use (step-up) transfmer to (increase potential difference/voltage and) reduce current; lower current means I 2 R/resistive losses reduced; large cable cross-section/good conduct used f cables so resistive losses reduced; Do not accept discussion of reduction of station distance from consumer. 3 max advantage: pumped stage on demand; disadvantage: but needs to be re-sted befe re-use; Answer must focus on comparison between tidal and pumped stage. Do not accept arguments based on unreliability of tide installation costs. 2 [13] IB Questionbank Physics 7