2 Question 1The continuous movement of water from the oceans to the air and back to the oceans is called the water cycle. The Sun heats the surface of the oceans, which causes the water to evaporate.a) How does the rate of evaporation depend onThe wind speed (1)The temperature (1)The humidity? (1)b) Explain how evaporation causes a cooling effect?(3)
3 Question 1 AnswerThe higher the wind speed the greater the rate of evaporation.The greater the temperature the greater the rate of evaporation.The higher the humidity, the slower the rate of evaporation.b)The most energetic molecules leave the surface of the liquid, so theaverage energy of kinetic energy of the remaining molecules is less.The temperature depends on the average kinetic energy, so it isreduced.
4 Question 2Compare the similarities and differences between the process of conduction in metals and non-metals. (6) In this question you will assessed on using good English, organising information clearly using specialist language where appropriate.
5 Questions 2 Answer Similarities Involve particles Atoms vibrate causing neighbouring atoms to vibrate so energy is passed along.DifferencesMetals have free electronsThese collide with other free electrons and ions passing energy along.This process is much more effective, so metals are better conductors.
6 Question 3In a hot water system water is heated by burning gas in a boiler. The hot water is then stored in a tank. For every 111 J of energy released from the gas, 100 J of energy is absorbed by the water in the boiler,Calculate the percentage efficiency of the boiler. (4)The energy released from the gas but not absorbed by the ‘boiler’ is wasted. Explain why this energy is of little use for further energy transfers. (1)The tank in the hot water system is surrounded by a layer of insulation. Explain the effect of the insulation on the efficiency of the hot water system. (3)
7 Question 3 Answer Efficiency = 90%. The energy becomes too spread out to use.The insulation reduced the rate at which energy is lost from the tank to the surroundings. The water in the tank will stay hotter for longer. This increases the efficiency of the hot water system.
8 Question 4 A light bulb transfers electrical energy into useful light energy and wasted energy to the surroundings. For every100 J of energy supplied to the bulb, 5 J of energy istransferred to light.Draw and label a Sanky diagram for the light bulb. (3)
9 Question 4 AnswerThe width of the arrow should be scaled to the number ofJoules.
10 Question 5 A student uses some hair straighteners. The straighteners have a power of 90 W. What is meant by ‘a power of 90 W’. (2)Calculate how many kilowatt-hours of electricity are used when the straighteners are used for 15 minutes. (3)The electricity supplier is charging 14 p per KWh. Calculate how much it will cost to use the straighteners for 15 minutes a day for one year. (2)
11 Question 5 answer 90 Joules of energy are transferred every second. E= KWhCost = £1.15
12 Question 6 Fluorescent bulbs are being replaced by compact A 25 W compact bulb costs £12, a filament bulb costs50p.A 25 W compact bulb gives out as much light as a 100Wfilament bulb.A filament bulb lasts for about 1000 hours; a compact bulblasts for a about 8000 hours, although significantly shorter ifthe bulb is turned on and off very frequently.Compare the advantages and disadvantages of buying a compact fluorescentbulb ratherthan filament bulbs. (6)
13 Question 6 Answers Advantages More efficient/4 times more efficient. Cheaper to useLast longer/lasts 8 times as long.Better for the environment.DisadvantagesMore expensive to buy/cost 24 times as much to buy.Disposal a problem because of mercury vapour.Shortened lifespan if turned on and off very frequently.
14 Question 7 Explain why step-up transformers are used in the National grid (2)
15 Question 7 AnswerTo increase the voltage on the cables and reduce powerlosses.
16 Question 8 Electromagnetic waves travel at a speed of 300 000 000 m/s. BBC 4 is transmitted using a wavelength of 1500metres.Calculate the frequency of these waves. (3)Write down the equation you use. Show clearly how youwork out your answer and give the unit.
18 Question 9 Give one example of each of the following from everyday life.Reflection of light (1)Reflection of sound (1)Refraction of light (1)Diffraction of sound (1)We do not normally see the diffraction of light in everyday life. Suggest a reason for this (2)
19 Question 9 AnswerAny example using mirror/water or a shiny smooth surface.Any example of an echo.Any example using a lens e.g. spectacles, cameras.Any example of hearing sound around a corner.The wavelength of light is very small, so diffraction only occurs when light passes through a narrow gap.
20 Question 10 Red shift from distant galaxies provides evidence for the big bang theory.What is meant by red shift? (2)Explain how red-shift provides evidence for the Big Bangtheory. (6)
21 Question 10 AnswersThe wavelength of light from a galaxy is shifted towardsthe red end of the spectrum and the galaxy is movingaway from us.Light from (most) galaxies is red shifted.The further the galaxy the bigger the red shift.The furthest galaxies are moving fastest.This shows that the universe is expanding.If the universe has always been expandingIt must have once been very small.