FORM 5 PHYSICS TIME: 2 hours

Transcription

1 DIRECTORATE FOR QUALITY AND STANDARDS IN EDUCATION Department of Curriculum Management Educational Assessment Unit Annual Examinations for Secondary Schools 2016 Track 3 FORM 5 PHYSICS TIME: 2 hours Name: 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 Class: 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 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 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 = the speed of light in air the speed of light in medium m = h i image distance = h o object distance Marks Grid: For the Examiners use ONLY Question Th. Prac Total Final Mark Mark Score Physics Form 5 Secondary Track Page 1 of 16

2 Section A: This section has 7 questions. Each question carries 10 marks (70 marks). 1. An archer uses his bow as shown in Figure 1. He pulls and then releases the string aiming his arrow towards a target. a) Tick the correct statement. The archer is doing work when holding the string in the position shown; after releasing the string to fire the arrow; as the string is pulled back to the position shown. [1] string bow arrow b) What type of energy is present when the bow is bent? Figure 1 [1] c) The moving arrow has both energy and gravitational potential energy. [1] d) The energy mentioned in (c) above changes into two other forms when the arrow hits the target. Name these forms of energy. [2] e) His friend prefers to use a slingshot (hand catapult) instead, as shown in Figure 2. He fired a small rock of mass 0.2 kg, vertically upwards so that it rises to a maximum height of 5 m. i) Underline: When the rock reaches its maximum height it has (elastic potential energy, kinetic energy, gravitational potential energy) [1] ii) Calculate the energy of the rock when it reaches its maximum height. Figure 2 iii) The rock eventually falls down back to the ground. Calculate the velocity with which it hits the ground. Page 2 of 16 Physics Form 5 Secondary Track

3 2. Peter and his family went to a magic show. The diagram below shows an optical illusion used by magicians. Peter said to his mother that it is sometimes called the ghost theatre illusion. Figure 3 a) Add rays to show how the image of the actor behind the glass sheet is formed. [2] b) Label clearly the angle of incidence i and the angle of reflection r. [2] c) The image formed is called a virtual image. What is meant by a virtual image? [2] d) When they arrived home from the magic show Peter wanted to show another optical phenomenon to his family. He shone a beam containing a mixture of red and blue light into a prism as shown in Figure 4. Red Light Screen Red + Blue Light Prism Figure 4 i) On the above diagram draw the path of the blue light as it passes through the prism and its position on the screen. [3] ii) Underline: This optical phenomenon is known as (diffraction, dispersion, focusing). [1] Physics Form 5 Secondary Track Page 3 of 16

4 3. Figure 5 shows the apparatus used to investigate the absorption of radiation from a radioactive source. Counter Source Geiger Muller tube Absorbing material Figure 5 Different absorbing materials are placed between the source and the G-M tube. The table below shows the count rate obtained with each of the four absorbers. Absorbing material Counts /s Air 500 Sheet of paper 501 Thin sheet of aluminium 315 Thin sheet of lead 100 a) The source is not emitting alpha particles. How can you tell from the above table? [2] b) Is the source emitting beta particles? Explain. [2] c) What is the evidence that γ-rays are being emitted? [2] d) In a different experiment, a science student placed a radioactive source in front of the Geiger- Muller tube and measured the count rate every 15 minutes. Time /min Count rate /min Corrected count rate /min i) From the table, calculate the background radiation. [1] Page 4 of 16 Physics Form 5 Secondary Track

5 ii) Define the term half-life. [1] iii) Estimate the half-life of this radioactive source using the information given in the above table. 4. Rose designed a device to compress crushed material for the school science fair. 10 cm 55 cm hinge piston lever beam 50 N F crushed material The hinge acts as a pivot. A force of 50 N is applied downwards on the right-hand end of the lever beam. Ignore the weight of the lever beam. a) State ONE of the conditions necessary for a body to remain in equilibrium. [1] b) Calculate the moment of the 50 N force about the hinge. [3] c) Underline: The 50 N force exerts a (clockwise, anticlockwise) moment about the hinge. [1] d) Using the law of moments, calculate the upward force F which the crushed material exerts on the piston. [2] e) The cross-sectional area of the piston in contact with the crushed material is m 2. Calculate the pressure exerted on the crushed material by the piston. [2] f) Underline. If the cross-sectional area of the piston is increased the pressure on the crushed material will (increase, remain the same, decrease). [1] Physics Form 5 Secondary Track Page 5 of 16

6 5. The Universe is everything we can touch, feel, sense, measure or detect. It includes living things, planets, stars, galaxies, dust clouds, light, and even time. The table below lists some facts about the Universe that may be True or False. a) Mark with a [ ] whether the statement is True or False. Statement True False i. The Moon can be observed only during the night. ii. The Sun is one of the millions of stars in our galaxy. iii. A planet is stationary and emits light. iv. There are 9 major planets in our solar system. v. The Earth spins on its axis once every 24 hours [5] b) The Earth experiences four seasons. State ONE factor that causes the seasons on Earth. [2] c) Astronomers have discovered a new Solar system. A diagram of this solar system is shown below. X Figure 6 Complete the following sentences by using words from the following list. universe, planet, orbit, star, milky way, gravitational, comet i) X is at the centre of the solar system. X is a [1] ii) A orbits around X. A is called a [1] iii) The force keeps A, B,C, D and E orbiting around X. [1] Page 6 of 16 Physics Form 5 Secondary Track

7 6. The diagram below shows a head-on collision between a car of mass 900 kg and a truck of mass 2000 kg. 15 m/s 20 m/s Figure 7 a) Calculate the momentum of the car before collision. [2] b) Calculate the momentum of the truck before collision. [2] c) Taking into consideration that it is a head-on collision, calculate the total momentum before collision. [1] d) What is the value of the total momentum after collision? [1] e) On another occasion, a driver accidentally leaves a packet resting on the roof of his car as shown in the diagram. i) What happens to the package when the driver brakes suddenly? [1] ii) Which of Newton s Laws explains your answer in (i) above? State this law. Figure 8 Physics Form 5 Secondary Track Page 7 of 16

8 7. A small private plane takes two minutes to travel between two Greek islands. a) Mark on Figure 9: i) the weight of the plane; [1] ii) the air resistance. [1] b) The graph below shows the journey of the plane between the two islands. Figure 9 Figure 10 Use the graph to answer the following questions. i) Calculate the acceleration of the plane as it takes off. ii) Mark on the graph the section where the plane flies at constant speed. Label as AB. [1] iii) How much time does it take the plane to decelerate and land on the other island? [1] iv) Calculate the total distance travelled by the plane. v) Each airport has a runway that is about 500 m long. Explain why these airports cannot cater for aeroplanes with a larger mass. Page 8 of 16 Physics Form 5 Secondary Track

9 Section B. This section has 5 questions. Each question carries 20 marks (100 marks). 8. This question is about electromagnetism. In 1831, Sir Michael Faraday began a great series of experiments in which he discovered electromagnetic induction. The principle discovered back then forms the basis of operation of a modern magnetic rechargeable torch. Figure 11 Figure 12 Figure 13 a) When the torch is shaken, the magnet moves through the coil and back again. This movement induces a voltage across the ends of the coil. The voltage is used to provide current to recharge the battery in the control unit. i) Explain why a voltage is induced. ii) State TWO ways to increase the induced voltage. iii) The torch uses an LED. What does LED stand for? Draw its symbol in the space provided. [2] iv) Why is an LED ideal for such a setup? b) Electromagnetic induction also occurs in a transformer. Figure 14 shows a typical transformer. Figure 14 Physics Form 5 Secondary Track Page 9 of 16

10 i) Briefly explain how the transformer works. ii) Why is the core made of soft iron? iii) What type of transformer is shown in Figure 14? [1] iv) If the primary coil has 8000 turns, calculate the number of turns in the secondary coil. v) State what would happen to the brightness of the lamp if the number of turns in the secondary coil was much less than that calculated in (iv) above. 9. This question is an experimental design about evaporation. Isaac likes to use aftershave after shaving. a) Explain in terms of molecules why the skin feels cool after applying aftershave. [2] b) Isaac accidentally left his aftershave plastic bottle on a windowsill where there is direct sunlight. After a few hours Isaac observes that the plastic bottle expanded as shown in Figures 15 and 16. Figure 15 Figure 16 Page 10 of 16 Physics Form 5 Secondary Track

11 i) While in direct sunlight the energy of the molecules increases and this results in a number of collisions with the wall of the container. The space between the molecules will also. [3] ii) How would the pressure differ if the bottle were made of glass? Explain. c) A scientist who works in a perfume manufacturing company produces two kinds of aftershaves. She would like to test which aftershave evaporates the quicker before choosing which one to put on the market. i) The scientist has the following apparatus at hand: cotton wool, clamp and stand, two thermometers, samples of each aftershave (aftershave X and aftershave Y) and a stopwatch. Describe what she has to do to determine which aftershave has the largest cooling effect. [5] ii) Mention ONE precaution that she should take to make sure the experiment is a fair experiment. iii) Which TWO variables should she plot on the graph? iv) Which of the two aftershaves could be smelt after a long period of time: the one which evaporates the fastest or the one which evaporates the slowest? Give a reason for your answer. Physics Form 5 Secondary Track Page 11 of 16

12 displacement /cm 10. This question is about waves. a) Mattias and Carl use a rope to propagate a wave as shown in Figure 17. distance /cm Figure 17 Determine: i) the amplitude of the wave. [2] ii) the wavelength of the wave. [2] iii) the frequency of the wave, if it travels at 3 m/s. b) Some cars have parking sensors fitted to them. Ultrasound is used in these sensors. Figure 18 i) Explain in your own words how the parking sensor uses ultrasound to work. ii) If the distance between the car and the wall is 170 cm, and the ultrasound is detected by the sensor 0.01 s later, calculate the velocity of the ultrasound wave. [4] Page 12 of 16 Physics Form 5 Secondary Track

13 iii) State what happens to the time taken for a transmitted wave to return back to the car if the car moves closer to the wall. iv) A typical ultrasound wave used in the car parking sensor has a frequency of Hz. Apart from the ultrasound emitting device, why is a buzzer sound also fixed to the parking sensor? v) Give ONE other use for ultrasound waves apart from parking sensors. 11. This question is about electrical circuits. A 9 V battery is connected as shown in the circuit of Figure V 4 X 13 Y 12 Z Figure 19 a) Find the total resistance between: i) points Y and Z; ii) points X and Z. b) Find the value of the resistance of the rheostat so that a current of 0.5 A flows through the circuit. Assume that the fuse has negligible resistance. [2] Physics Form 5 Secondary Track Page 13 of 16

14 c) Calculate the voltage across the rheostat. [3] d) What is the function of the fuse in a circuit? [2] e) Calculate the maximum current that can flow through the circuit. Explain how this can be achieved without changing the circuit. [2] f) Three fuses are available: 0.2 A, 0.6 A and 1.0 A. Which of these three fuses is the most suitable to allow the maximum current calculated in part (e) to flow through it? [1] g) On the circuit of Figure 19, draw a voltmeter to measure the voltage across the rheostat. [2] h) Should the resistance of the voltmeter be high or low? Explain. [3] 12. This question is about density and thermal energy. Two students, Jasmine and Jake were given an unknown solid of mass 340 g. They had to determine the material that the solid was made of. Jasmine and Jake decided to find the density of the solid first. a) Use the diagram to determine the volume of the unknown solid. [2] Figure 20 Page 14 of 16 Physics Form 5 Secondary Track

15 b) Calculate the density of the unknown solid. [2] c) Use the table below to determine the material the solid is made up of. Explain how you arrived at your answer. Material Aluminium Lead Rhodium Silver Density g/cm [2] d) To find the specific heat capacity of the solid, Jake used a 950 g block of the same solid with two holes drilled in it. A thermometer was placed in one hole and a 95 W heater was placed in the other. He lagged the solid using wool. The heater was switched on and the temperature was recorded every 3 minutes. The results are shown in the table below: Temperature / o C Time /min i) Plot a graph of Temperature on the y-axis against Time on the x-axis. [5] ii) Find the gradient of the graph in order to determine the temperature rise per minute. iii) Calculate the energy supplied by the 95 W heater to the solid in 12 minutes assuming there are no heat losses. iv) Calculate the specific heat capacity of the unknown solid of mass 950 g. v) Explain why the solid was lagged using wool. Physics Form 5 Secondary Track Page 15 of 16

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