DIRECTORATE FOR QUALITY AND STANDARDS IN EDUCATION Department of Curriculum Management Educational Assessment Unit Track 3 Annual Examinations for Secondary Schools 2015 FORM 5 PHYSICS Time: 2 hours Name: Class: Answer ALL questions in the spaces provided on the Examination Paper. All working must be shown. The use of a calculator is allowed. Where necessary take the acceleration due to gravity g = 10 m/s 2. Density m = ρ V Pressure P = ρ g h F = P A Moments Energy Moment = F perpendicular distance PE = m g h KE = 1 2 mv2 Work Done = F s Work Done = Energy Converted E = P t Force F = m a W = m g Motion Electricity total distance (u + v) t Average Speed = total time s = s = ut + 1 2 2 at2 v = u + at v 2 = u 2 + 2as Momentum = m v Q = I t V = I R E = Q V P = I V R L/A E = I V t R T = R 1 + R 2 + R 3 1 R T = 1 R 1 + 1 R 2 Electromagnetism Heat Waves Radioactivity N 1 N 2 = V 1 V 2 ΔQ = m c Δθ real depth η = apparent depth v = f λ f = 1 T A = Z + N η = speed of light in air speed of light in medium m = h i image distance = h o object distance Marks Grid: For the Examiners use ONLY Question 1 2 3 4 5 6 7 8 9 10 11 12 Th. Prac Total Final Mark Mark 10 10 10 10 10 10 10 20 20 20 20 20 170 30 200 100 Score Physics Form 5 Secondary Track 3 2015 Page 1 of 12
Section A: This section has 7 questions. Each question carries 10 marks (70 marks). 1. A solar water heater is shown in Figure 1. a) The solar collector is dark coloured. Why? [1] b) Why is the back of the solar collector well insulated? [2] c) Why is the storage tank placed above and not below the solar collector? hot water out cold water in Figure 1 storage tank solar energy solar collector d) A student is told that heat from the sun reaches the solar collector by convection. Is this statement correct? Explain. e) Why are the pipes used in the solar water heater made of a metal such as copper? f) The pipes are also long and in the shape of a coil. Why? 2. Maria places two iron cores in a cardboard tube as shown in Figure 2. When she closes the switch she observes that the iron cores move. plotting compass coil iron cores X Y battery switch Figure 2 cardboard tube Figure 2 a) Draw arrows to represent the direction of the current through the coil. [1] b) End X becomes a pole while end Y becomes a pole. [2] c) In which direction do the iron cores move? Explain. d) Draw an arrow on each plotting compass to indicate the direction of the magnetic field. [2] e) State one way by which the magnetic field can be made stronger. f) The polarity of the battery is reversed. Explain why the movement of the iron cores is unchanged. Page 2 of 12 Physics Form 5 Secondary Track 3 2015
3. The Andromeda galaxy is 2.5 million light years away from Earth. a) Name the instrument used to observe such a distant galaxy. [1] b) What is a galaxy made up of? c) Define the term light year. d) Change 1 light year to metres. The speed of light is 3 10 8 m/s. [3] e) Name one benefit of space exploration. f) Name one question about the Universe that is still unanswered to this day. 4. Tony is driving his car at a speed of 20 m/s. He sees a dog sitting in the middle of the road 75 m ahead. The car moves a distance of 12 m before he starts to apply the brakes. He eventually manages to stop the car 6 seconds after braking. a) Calculate his reaction (thinking) time. b) Calculate his braking distance. c) Work out the total stopping distance. d) Using the answer in part c, state whether he will hit the dog. [1] e) Find the deceleration of the car. sees dog starts braking Figure 4 Figure 3 f) Given that the mass of the car is 1500 kg, determine the braking force needed to stop the car. g) Tony accelerates to 30 m/s. His reaction time (increases, decreases, remains the same). [1] dog Physics Form 5 Secondary Track 3 2015 Page 3 of 12
5. a) Daniela and Thomas are carrying out an experiment on electrostatics. i) Daniela argues that a neutral perspex (acetate) strip has no charges at all. Do you agree? Explain. ii) When Daniela rubs the perspex strip with a cloth, it acquires a positive charge because are transferred from the to the [3] b) Lightning occurs when there is a very large amount of static electricity in clouds. During a lightning strike the average current flowing is 45 000 A. The amount of electric charge delivered during the strike is 5 C. i) Calculate the duration of a lighting strike. Figure 5 ii) Given that the energy dissipated is 6 10 8 J (600 000 000 J), calculate the voltage present. 6. In the hydraulic jack shown in Figure 6, the lever lever is pushed down several times making the van piston A piston B rise by a certain height each time. The valves allow the oil to flow in one direction. a) State the advantage of using a hydraulic system. oil tank valve 1 tap (closed) valve 2 Figure 6 b) Why are liquids used in hydraulic systems? c) Which valve prevents the van from going down after it is lifted? d) Predict what happens when the tap is opened. e) The area of piston A is 0.0004 m 2 while that of piston B is 8 m 2. If the van s mass is 2200 kg, calculate: i) the pressure exerted by the van on the liquid. ii) the force applied by the lever on piston A. Page 4 of 12 Physics Form 5 Secondary Track 3 2015
7. Noel carried out an experiment on moments using a metre ruler. a) State the two conditions needed for a system to be in equilibrium. b) The metre ruler he sets up is shown in Figure 7. It is pivoted at its midpoint but is not balanced. 0.5 m 0.1 m 0.4 m 2N 2N 1N Figure 7 i) Show (through calculation) that the resultant moment is 0.3 N m. ii) State the direction in which the metre ruler turns. [1] c) A builder needs to move a concrete brick using a wheelbarrow. Figure 8 shows two different wheelbarrows having the same brick placed in a different position. wheelbarrow A wheelbarrow B Figure 8 i) Explain why the concrete block in wheelbarrow B is not producing a turning effect. ii) Explain, by making use of the terms moment, force and perpendicular distance, the advantage of having longer handles as in wheelbarrow B. Physics Form 5 Secondary Track 3 2015 Page 5 of 12
Section B. This section has 5 questions. Each question carries 20 marks (100 marks). 8. This question is about motion. a) Daria and Max are supplied with an air track, a glider, a light gate and a data logger as shown in Figure 9. The data logger measures the velocity of the glider as it passes through the light gate. light gate data logger glider air track Figure 9 i) Name an additional apparatus that the students need to calculate the kinetic energy of the glider. ii) Their teacher asks them to investigate how the kinetic energy of the glider depends on its velocity. Describe the method they should use, including how they can present their results. [4] iii) Daria and Max predict that the kinetic energy increases with increasing velocity. Do you agree with this prediction? [1] b) A toy truck of mass 1.25 kg moving at 3 m/s collides with a stationary ball of mass 0.25 kg. After the collision, the toy truck moves at 2 m/s, while the ball moves with a different velocity. i) Calculate the total momentum before collision. ii) What is the total momentum after collision? Explain. iii) Calculate the velocity of the ball after the collision. iv) Show that the total kinetic energy before collision is 5.625 J. Page 6 of 12 Physics Form 5 Secondary Track 3 2015
v) Show that the total kinetic energy after the collision is equal to the total kinetic energy before collision. 9. This question is about electricity. a) Bradley and Diana are required to find the electrical energy, E, consumed in 5 minutes by a DVD player. They take readings off the joulemeter every minute as shown in the table of results below. Electrical energy consumed E / J 0 1500 3000 4500 5000 7500 time t / minutes 0 1 2 3 4 5 i) Plot a graph of electrical energy E in joules consumed by the DVD player (y-axis) against the time t in minutes (x-axis) on the graph paper provided. [5] ii) Bradley reads incorrectly the quantity of electrical energy E consumed by the DVD after 4 minutes. Use your graph to determine the correct value of E after 4 minutes. iii) Is electrical energy E consumed by the DVD directly proportional to time? Explain your answer. iv) Calculate the time in seconds during which the DVD is turned on. v) From your graph or otherwise calculate the power of the DVD. vi) Diana watches a 150-minute film on the DVD player. Calculate the number of kwh consumed during this time. Physics Form 5 Secondary Track 3 2015 Page 7 of 12
b) The diagram shows a power ring circuit and an incompletely connected 13-A socket. i) From the diagram, what indicates that wire P is the live wire? [1] ii) State the colour of the insulation of the: 1. Neutral from mains supply 13-A socket P Q R 30-A fuse Figure 10 wire: [1] 2. Earth wire: [1] iii) Draw the two missing socket connections to the ring circuit. [2] 10. This question is about radioactivity and half-life. a) Figure 11 shows two instruments used in measuring the activity of radioactive substances. Radioactive source Q Counte R i) Name instrument Q. [1] ii) Name instrument R. [1] Figure 11 iii) Which of the above instruments is used to detect radiation emitted by unstable nuclei? iv) Which of the above instruments gives the number of unstable nuclei decaying (breaking down) over a period of time? b) Gregg finds out that the rate of decay of a newly discovered radioactive isotope X is 1025 counts/minute. He notices that when the radioactive isotope X is not present, the reading drops to 25 counts/minute. i) Explain why the count rate does not fall to zero when the radioactive isotope X is not present. ii) Name two sources of this radiation. Page 8 of 12 Physics Form 5 Secondary Track 3 2015
c) While investigating the half-life of radioactive isotope X, Gregg records the data in the table below. Time / (hours) 0 0.5 1.0 1.5 2.0 2.5 Total count rate / (counts/min.) 1025 863 622 523 447 Background count rate / (counts/min.) 23 25 22 23 27 Corrected count rate / (counts/min.) 1000 840 710 600 420 i) Complete the following statement about half-life: Half-life is the time taken for the nuclei of a sample of a radioactive substance to decay. [1] ii) Complete the missing values in the above table. [3] iii) Use the table to calculate the half-life of the radioactive isotope X. d) Calculate the mass of radioactive isotope X which remains after 6 h given that the initial mass of this isotope was 8 g. [3] e) Name: i) two main uses of radioactive isotopes. ii) two main safety measures when dealing with radioactive substances. Physics Form 5 Secondary Track 3 2015 Page 9 of 12
11. This question is about the motor effect of an electric current. a) Robert sets a loosely held vertical wire PQ between the poles of a powerful magnet and closes the switch S. He observes that the wire PQ moves. P S I N S R Q A Figure 12 i) Underline: The wire section PQ moves (inwards, outwards, left, right). [1] ii) Name the force causing the wire PQ to move. [1] iii) Name the rule which helps Robert determine the direction of movement of wire section PQ. iv) Name two ways through which the force acting on wire section PQ can be decreased. v) State two ways in which this force can be made to act in the opposite direction. vi) Why is the rheostat R included in the circuit? vii) State what change, if any, is observed when the battery is removed and replaced by a low frequency a.c. supply. b) Figure 13 below represents a d.c. motor. B C N S A D + Figure 13 Page 10 of 12 Physics Form 5 Secondary Track 3 2015
i) Coil section experiences a force pushing it out of the plane of the paper when the electric current flows through the coil. [2] ii) Which section of the coil does NOT experience a force? [2] iii) Give a reason why the section of coil referred to in question (ii) does not experience a force. iv) State the direction of rotation of the motor shown in Figure 13. [2] v) Name an appliance which makes use of an electric motor. 12. This question is about measuring the specific heat capacity of sea water. a) Nadia and Joanne are required to find the specific heat capacity of a sample of sea water collected from Golden Bay. They are supplied with the following apparatus: beaker containing some sea water; d.c. immersion heater; d.c. power supply; joulemeter; lagging material; lid; electronic balance; thermometer and a stirrer. Describe how Nadia and Joanne should carry out their investigation. Your answer should include: i) a labelled diagram of the experimental setup. [3] ii) the three measurements required to find the specific heat capacity of sea water apart from the room temperature. iii) the three items of apparatus required to collect these measurements. Physics Form 5 Secondary Track 3 2015 Page 11 of 12
/ C iv) Name two precautions which must be taken during this investigation. b) Nadia plots a graph of the change in temperature Δθ of sea water against heat energy supplied Q as shown below. 6 Graph of temperature change against heat energy supplied Q 5 4 3 2 1 0 0 2000 4000 6000 8000 10000 12000 Q / J Use Nadia s graph to: i) calculate the change in temperature of the mass of sea water when the quantity of heat supplied to the sea water is 5000 J. ii) predict the quantity of heat required to raise the temperature by 6 C. [2] iii) find the specific heat capacity of sea water given that its mass is 0.5 kg. iv) determine the room temperature, given that the final temperature reached by sea water when 10000 J of heat energy are supplied is 20 C. c) What do you notice from Nadia s graph that shows that the beaker containing the sea water is very well-lagged? Page 12 of 12 Physics Form 5 Secondary Track 3 2015