The graphs show the voltage across two different types of cell as they transfer the last bit of their stored energy through the torch bulb.

Transcription

1 Physics P2 Higher Questions Part 2 Q1. A small torch uses a single cell to make the bulb light up. (a) The graphs show the voltage across two different types of cell as they transfer the last bit of their stored energy through the torch bulb. Describe the differences that the graphs show between the two types of cell. (3) (b) The diagram shows how bright the torch bulb is for different voltages. From the point when the voltage of each cell starts to fall, how long will the bulb stay lit: (i) with the ordinary cell? Page 1

2 (ii) with the nicad cell? (4) (c) When the voltage across the bulb falls to half, the current through the bulb falls by less than half. Why is this? (3) (Total 10 marks) Q2. When atoms of uranium 238 (U 234 ) decay they produce another radionuclide called thorium 234 (Th 234 ) Thorium 234 (Th 234 ) decays by emitting beta radiation. (i) What does beta radiation consist of? (ii) Thorium 234 (Th 238 ) decays to form protactinium 234 (Pa 234 ). What differences are there between the nucleus of a protactinium 234 (Pa 234 ) atom and the nucleus of a thorium 234 (Th 234 ) atom? (Total 3 marks) Page 2

3 Q3. The graph shows how the amount of radiation emitted by a sample of the radionuclide uranium 238 (U 238 ) changes as time passes. (a) What is the half-life of uranium 238 (U 238 )? (You should show how you obtained your answer. You may do this on the graph if you wish.) Answer... (3) (b) What fraction (or percentage) of the uranium 238 (U 238 ) atoms will have decayed after 9 billion years? (c) Uranium 238 (U 238 ) decays through a long series of intermediate radionuclides to stable atoms of the isotope lead 206 (Pb). A sample of igneous rock contains 3 atoms of uranium 238 (U 238 ) for every atom of lead 206 (Pb 206 ). (i) The intermediate radionuclides are not important when estimating the age of Page 3

4 the rock. Explain why. (ii) Estimate the age of the rock. (You should explain how you obtained your answer.) Answer... billion years (3) (Total 8 marks) Q4. The brick shown in the diagram is being pushed but it is not moving. (a) The pushing force does not make the brick move. Explain why.. Page 4

5 (b) The weight of the brick does not make it move downwards. Explain why. (c) A bigger pushing force does make the brick slide across the table. Write down one thing that the sliding brick will do to the surface of the table.... (Total 3 marks) Q5. Describe, in as much detail as you can, the life history of a star like our Sun (Total 6 marks) Page 5

6 Q6. The graph shows the speed of a runner during an indoor 60 metres race. (a) Calculate the acceleration of the runner during the first four seconds. (Show your working.) (3) (b) How far does the runner travel during the first four seconds? (Show your working.) (3) (c) At the finish, a thick wall of rubber foam slows the runner down at a rate of 25 m/s 2. The runner has a mass of 75kg. Calculate the average force of the rubber foam on the runner. (Show your working.) Page 6

7 Answer... newtons (N) (Total 8 marks) Q7. Doctors sometimes need to know how much blood a patient has. They can find out by using a radioactive solution. After measuring how radioactive a small syringe-full of the solution is they inject it into the patient s blood. They then wait for 30 minutes so that the solution has time to become completely mixed into the blood. Finally, they take a syringe-full of blood and measure how radioactive it is. Example: Page 7

8 If the doctor injects 10 cm 3 of the radioactive solution and this is diluted 500 times by the blood there must be = 5000 cm 3 of blood. (a) After allowing for background radiation: 10 cm 3 of the radioactive solution gives a reading of 7350 counts per minute; a 10 cm 3 sample of blood gives a reading of 15 counts per minute. Calculate the volume of the patient s blood. (Show your working.) (4) Radiation from radioactive substances can harm your body cells. (b) The doctor s method of estimating blood volume will not be completely accurate. Write down three reasons for this (3) (c) The doctors use a radioactive substance which loses half of its radioactivity every six hours. Explain why this is a suitable radioactive substance to use. Page 8

9 (Total 9 marks) Q8. (a) When an atom of thorium-232 decays, an alpha (α) particle is emitted from the nucleus. An atom of radium is left behind. An alpha particle consists of two protons and two neutrons. We can represent this radioactive decay in a special kind of equation: Thorium-228 is also radioactive. Atoms of this isotope also decay by emitting an alpha particle and producing an isotope of radium. Complete the equation for this decay. (4) (b) An atom of radium-228 decays by emitting a beta (β) particle from the nucleus. A beta particle is in fact an electron (symbol ). The effect of this is to change a neutron into a proton. An atom of actinium remains. This type of decay can also be represented by an equation: Page 9

10 This isotope of actinium is radioactive. An atom of actinium-228 also decays by emitting a beta particle. An isotope of thorium is left behind. Complete the equation for this decay. (4) (c) Thorium-232 eventually decays to the stable isotope lead-208. All the steps in this process can be shown on a diagram. (i) Complete the sentences: During the decay from (A) to (B) a... particle is emitted. During the decay from (B) to (C) a... particle is emitted. Page 10

11 During the decay from (E) to (F) a... particle is emitted. During the decay from (I) to (J) a... particle is emitted. (ii) The table shows how long it takes for half of the atoms of each isotope to decay. A rock sample contains: many atoms of thorium 232 even more atoms of lead 208 hardly any atoms of any of the other isotopes shown on the diagram Explain this as fully as you can. (3) Page 11

12 (Total 13 marks) Q9. (a) The amount of damage caused when a car collides with a wall depends on the amount of energy transferred. If the speed of a car doubles, the amount of energy transferred in a collision increases four times. Explain, as fully as you can, why this is so. (3) (b) The diagram shows a car and a lorry about to collide. When they collide, the two vehicles become tightly locked together. (i) Calculate the speed of the vehicles immediately after the collision. (Show your working. There is no need to change to standard units.) Page 12

13 Answer... km/h (6) (ii) The collision between the car and the lorry is inelastic. Explain, in terms of energy, what this means. (Total 10 marks) Q10. The energy radiated by a main sequence star like the Sun is released by a nuclear fusion reaction in its core. Read the following information about this reaction then use it to answer the questions below. The net result of the nuclear fusion reaction is that four hydrogen nuclei produce one helium nucleus. There is a loss of mass of 0.7%. For nuclear fusion to occur nuclei must collide at very high speeds. The energy released during the reaction can be calculated as shown: energy released [J] = loss of mass [kg] (speed of light [m/s²]) (The speed of light is m/s) (a) Calculate the energy released when 1g of hydrogen fuses to form helium. (Show your working.) (4) Page 13

14 (b) The table shows the lifetimes and surface temperatures of main sequence stars with different masses. MASS OF STAR [SUN = 1] LIFETIME ON MAIN SEQUENCE [MILLION OF YEARS] SURFACE TEMPERATURE * [KELVIN] [* The higher the surface temperature of a star, the higher the temperature and pressure in its core.] (i) Describe the relationship between the lifetime of a main sequence star and its mass. (ii) Suggest an explanation for this relationship. (3) (Total 9 marks) Page 14

15 Q11. When a gun is fired, a very large force acts on the bullet for a very short time. The change in momentum of the bullet is given by the following relationship: force (N) time(s) = change in momentum (kg m/s) (a) An average force of 4000 newton acts for 0.01 seconds on a bullet of mass 50g. Calculate the speed of the bullet. (Show your working.) Answer... m/s (4) (b) The bullet is fired horizontally. In the short time it takes for the bullet to reach its target, its horizontal speed has fallen to 80% of its initial speed. (i) Explain why the speed of the bullet decreases so quickly. (ii) Calculate the percentage of its original kinetic energy the bullet still has when it reaches its target. (Show your working.) (4) (Total 10 marks) Page 15

16 Q12. At the very high temperatures in the sun, hydrogen is converted into helium. It takes four hydrogen nuclei to produce one helium nucleus. The table shows the relative masses of hydrogen and helium nuclei. (a) Use these figures to calculate what happens to the mass of the sun as hydrogen is converted to helium. (3) (b) Use your answer to part (a) to explain how the sun has been able to radiate huge amounts of energy for billions of years. (Total 5 marks) Page 16

17 Q13. Carefully read the following extract from a safety leaflet. Then answer the questions. An RCD adaptor is an automatic safety switch. It should be used when there is a particular risk of electric shock. For example, it is recommended that it is used with an electric lawnmower. Inside one make of RCD is an electromagnet that holds the switch closed so that the RCD is switched on. An electronic circuit in the RCD monitors the difference between the current in the live wire and the current in the neutral wire. If something goes wrong and this difference is greater than 30 milliamps then the RCD will trip (= switch off) within 40 milliseconds. (a) Suggest two reasons why there is a particular risk of an electric shock when using an electric lawnmower (b) Why will there be a difference between the current in the live wire and the current in the neutral wire if something goes wrong? (c) (i) Use the words charge, current and time to write an equation which shows the relationship between them.... (ii) Calculate how much charge flows when a current of 30 milliamps passes for 40 milliseconds. Clearly show how you get to your answer and give the unit. Page 17

18 Charge =... (3) (Total 7 marks) Q14. The drawing shows a food processor. It has an electric motor. Inside is a blade which spins round and cuts up the food. The food processor is designed to transfer electrical energy to kinetic energy. However some of the energy is wasted as heat and sound. The power input to the food processor is 1150 W. The power of the spinning blade is 900 W. (i) Calculate how much energy is wasted when the food processor is used for two minutes. Show clearly how you get to your answer and give the unit. power = Page 18

19 Energy =... (3) (ii) Why does the food processor produce sound when it is switched on? (Total 4 marks) ## A combination oven can cook food by using three methods; a microwave generator, a grill and a heating element. voltage microwave power (max) grill power convection heater power 230 V 900 W 1300 W 1200 W (a) What is the current when the oven is operating using full microwave power? Give the equation and show your working. Current =... A (3) (b) It is possible to cook using infrared radiation, from the grill, and microwaves. What is the maximum current in the oven when using both together? Page 19

20 Current =... A (c) For baking and roasting, the microwave is used at 450 W and the convection heating element is on fully at 1200 W. A thawed or fresh medium-sized chicken takes 30 minutes to cook. Calculate the energy transferred in kilowatt-hours. Use: units (kwh) = power (kw) time (h) Energy =... kwh (d) Why is a combination oven of this sort more economical than a convection-only oven? (Total 8 marks) Q16. Mira and Susan are rock climbing. They are using a nylon climbing rope. Mira has fastened herself to the rock face and to one end of the rope. The other end of the rope is fastened to Susan. This means that, if Susan falls, the rope will hold her. Susan weighs 540 N. Page 20

21 (a) (i) Use the words distance, force and work to write an equation which shows the relationship between them... (ii) What vertical distance up the rock face does Susan climb when she does 2000 J of work against gravity? Show your working and give your answer to the nearest 0.1 m Distance =... metres Page 21

22 (iii) How much gravitational energy will Susan gain when she does 2000 J of work against gravity?... (b) The climbers dislodge a 3 kg stone which falls down the rock face. What is the speed of the stone when its kinetic energy is 600 J? kinetic energy = mass speed 2 Show clearly how you get to your answer and give the unit. Speed =... (3) (c) The climbing rope is made of nylon. Nylon is very strong. Another advantage is that it stretches. This means that, if Susan falls, it transfers some of her kinetic energy to elastic (or strain) energy at the end of the fall. Explain, in terms of force and deceleration, what would happen if Susan fell and the climbing rope did not transfer any of her kinetic energy to elastic energy. (3) (Total 10 marks) Page 22

23 Q17. The diagram shows a type of electric immersion heater in a hot water tank. These hot water tanks are normally found in airing cupboards. Information on the immersion heater states: 230 V 10 A (a) (i) What is the equation which shows the relationship between power, current and voltage?... (ii) Calculate the power of the heater. Show clearly how you get to your answer and give the units.... Power =... (b) (i) What rating of fuse should be in the immersion heater circuit?... Page 23

24 (ii) There are three wires in the cable to the immersion heater. Two of the wires are connected to the immersion heater. The third wire is connected to the copper tank. Explain the function of this third wire and the fuse in the circuit (3) (c) (i) What is the equation which shows the relationship between resistance, current and voltage?... (ii) Calculate the resistance of the heater. Show clearly how you get to your answer and give the units.... Resistance =... (Total 10 marks) Q18. A 1 N weight is tied to a 30 cm long piece of elastic. The other end is fixed to the edge of a laboratory bench. The weight is pushed off the bench and bounces up and down on the elastic. Page 24

25 The graph shows the height of the weight above the floor plotted against time, as it bounces up and down and quickly comes to rest. (a) Mark on the graph a point labelled F, where the weight stops falling freely. (b) Mark on the graph a point labelled S, where the weight finally comes to rest. Page 25

26 (c) Mark two points on the graph each labelled M, where the weight is momentarily stationary. (Total 3 marks) Q19. The drawing shows an experiment using a low voltage supply, a joulemeter, a small immersion heater and a container filled with water. The voltage was set at 6 V d.c. The reading on the joulemeter at the start of the experiment was and 5 minutes later it was (i) Use the equation: voltage = to work out the total charge which flowed through the immersion heater in five minutes. Clearly show how you get to your answer and give the unit. Page 26

27 Charge =... (3) (ii) Calculate the current through the immersion heater during the 5 minutes. Write the equation you are going to use, show clearly how you get to your answer and give the unit. Current =... (3) (Total 6 marks) Q20. The drawing shows an investigation using a model steam engine to lift a load. Page 27

28 In part of the investigation, a metal block with a weight of 4.5 N was lifted from the floor to a height of 90 cm. (a) Explain what causes the weight of the metal block. (b) (i) What is the tension in the string when the block is lifted at a steady speed? Page 28

29 (ii) Explain your answer to part (b) (i). (c) (i) Calculate the work done in lifting this load. Write the equation you are going to use, show clearly how you get to your answer and give the unit. Equation... Work =... (3) (ii) How much useful energy is transferred to do the work in part (c) (i)? (d) In another part of the investigation, 250J of work is done in one minute. Use the equation: power = to work out the useful power output. Give the unit. Power =... (Total 10 marks) Q21. The flowchart shows four stages thought to occur in the evolution of a star such as our Sun. Page 29

30 At a particular time a star might have reached one of these stages or be between stages or be at a further stage. What period in its evolution has our star, the Sun, reached?... (Total 1 mark) ## The isotope of sodium with a mass number of 24 is radioactive. The following data were obtained in an experiment to find the half-life of sodium-24. Time in hours Count rate in counts per minute (a) Draw a graph of the results and find the half-life for the isotope. On the graph show how you obtain the half-life. Page 30

31 Half-life =... hours (4) (b) Sodium-24 decays by beta emission. The G.M. tube used in the experiment is shown in the diagram. Each beta particle which gets through the glass causes a tiny electric current to pass in the circuit connected to the counter. Page 31

32 (i) Why must the glass wall of the G.M. tube be very thin? (ii) Why is this type of arrangement of no use if the radioactive decay is by alpha emission? (c) Sodium chloride solution is known as saline. It is the liquid used in drips for seriously-ill patients. Radioactive sodium chloride, containing the isotope sodium-24, can be used as a tracer to follow the movement of sodium ions through living organisms. Give one advantage of using a sodium isotope with a half-life of a few hours compared to using an isotope with a half-life of: (i) five years; (ii) five seconds (Total 8 marks) Page 32

33 Q23. The following specification is taken from the instruction booklet of a combination microwave oven. voltage er required owave l (Roast/Bake) l (Grill) vection put power owave vection heater heater owave frequency V 50 Hz kw kw kw kw kw W 0 W 0 W 0 MHz (a) (i) What is the current when the oven is being used to cook in the dual (roast/bake) mode? Show clearly how you work out your answer. Current =... A (ii) Calculate the resistance of this combination microwave oven when it is being used in the dual (roast/bake) mode. Show clearly how you work out your answer and give the units. Page 33

34 Resistance =... (3) (b) What is the percentage efficiency of the oven when it is working in the microwave mode? Efficiency = 100% Percentage efficiency =... % (Total 7 marks) Q24. A bouncy ball is dropped vertically from a height of 2.00 m onto the floor. The graph shows the height of the ball above the floor at different times during its fall until it hits the floor after 0.64 s. Page 34

35 (a) What is the average speed of the ball over the first 0.64 s? Show clearly how you work out your answer Average speed =... m/s (b) After it hits the floor the ball bounces back to a height of 1.25 m. It reaches this height s after it was dropped. Plot this point on the grid above and sketch a graph to show the height of the ball above the floor between s and 1.16 s. (3) (c) (i) The ball bounces on the floor 0.64 s after being dropped. How long after being dropped will it be before it bounces a second time? Page 35

36 (ii) What distance will the ball travel between its first and second bounce? (d) The ball was held stationary before being dropped. On the graph and your sketch mark two other points X 1 and X 2, where the ball is stationary, and in each case explain why the ball is not moving. X X (Total 8 marks) Q25. The diagram shows the fuel gauge assembly in a car. The sliding contact touches a coil of wire and moves over it. The sliding contact and the coil form a variable resistor. The sliding contact is connected to a float via a pivot. The fuel gauge indicator is an ammeter. When the petrol level changes, the resistance of the circuit changes. This causes the pointer in the fuel gauge indicator to move. Page 36

37 (a) Use standard symbols to draw a circuit diagram for the fuel gauge assembly. (3) Page 37

38 (b) How will the current in the circuit change as the level of petrol in the tank falls? Explain the reason for your answer. (Total 5 marks) Q26. The Sun at the centre of our solar system is a star. (a) The Sun contains nuclei of the heaviest elements. Atoms of these heaviest elements are also present in the planets of the solar system. What does this suggest about the material from which the solar system is formed? (b) Stars form from gas (mostly hydrogen) and dust. Page 38

39 Describe, in as much detail as you can, what forces allow a stable star to exist and how the star may eventually form a black hole. To gain full marks in this question you should write your ideas in good English. Put them into a sensible order and use the correct scientific words. (6) (Total 7 marks) Page 39

40 Q27. A car which is moving has kinetic energy. The faster a car goes, the more kinetic energy it has. The kinetic energy of this car was J when travelling at 30 m/s. Calculate the total mass of the car. Show clearly how you work out your answer and give the unit Mass of the car =... (Total 5 marks) Q28. (technetium) is produced by the radioactive decay of (molybdenum). What change occurs in the nucleus of a molybdenum atom when this happens? (Total 1 mark) Page 40

41 Q29. The table gives the properties of some radionuclides (radioactive isotopes). Radionuclide Half life Main type of radiation emitted Radon seconds Alpha Americium years Alpha Phosphorus days Beta Strontium years Beta Technetium-99 6 hours Gamma Cobalt-60 5 years Gamma (i) Which radionuclide would be best for monitoring the thickness of aluminium foil?... Explain the reason for your answer. (ii) Which radionuclide would be best for acting as a tracer inside the human body?... Explain the reason for your answer. (Total 4 marks) Page 41

42 Q30. (a) (i) Describe the structure of alpha particles. (ii) What are beta particles? (b) Describe how beta radiation is produced by a radioactive isotope. (Total 4 marks) Q31. One theory of the origin of the Universe was that billions of years ago all matter was in one place, then it exploded ( big bang ). Describe, in as much detail as you can, how our star (the Sun) formed from the time when there was just dust and gas (mostly hydrogen) up to now when it is in its main stable period. To gain full marks in this question you should write your ideas in good English. Put them into a sensible order and use the correct scientific words Page 42

43 (Total 5 marks) Q32. A rocket has a mass of 5000 kg and is travelling at a speed of 600 m/s. Page 43

44 Calculate the rocket s kinetic energy in kilojoules. Show your working Kinetic energy =... kj (Total 3 marks) Q33. A rollercoaster car stops above a vertical drop. Suddenly it falls under gravity. The drop is 60 metres high and at the bottom of the drop the car travels at 125 km/h. The acceleration experienced by the people in the car is 10 m/s 2. The mass of the car and its passengers is 1210 kg. Calculate the force exerted on the car and its passengers. Show your working Force =... N (Total 3 marks) Page 44

45 Q34. Iodine-131 ( 131 I) is a radioactive isotope used in medicine. The graph shows how the count rate of a sample of iodine-131 changed over 24 days. (i) Use the graph to calculate the half-life of iodine-131. To obtain full marks you should show clearly how you work out your answer. Half-life... days (ii) Iodine-131 is used to destroy cancer cells in the human thyroid gland. Explain why the length of the half-life of iodine-131 is important in this use. Page 45

46 (Total 4 marks) Q35. Iodine-131 ( 131 I) is a radioactive isotope used in medicine. The graph shows how the count rate of a sample of iodine-131 changed over 24 days. (i) Use the graph to calculate the half-life of iodine-131. To obtain full marks you should show clearly how you work out your answer. Half-life... days (ii) Iodine-131 is used to destroy cancer cells in the human thyroid gland. Explain why the length of the half-life of iodine-131 is important in this use. Page 46

47 (Total 4 marks) Page 47