bedok south Prelim 2020 4E5N Sc(Phy) P2

BEDOK SOUTH SECONDARY SCHOOLPRELIMINARY EXAMINATION 2020 4E5N CANDIDATENAME CLASS REGISTERNUMBER SCIENCE (PHYSICS, CHEMISTRY)Paper 2 Physics Candidates answer on the Question Paper.No Additional Materials are required. 5076/0228 Aug 2020 1 h 15 min READ THESE INSTRUCTIONS FIRST Write your class, register number and name on thecover page.You may use a soft pencil for any diagrams, graphsor rough working.Write in dark blue or black ink.Do not use paper clips, highlighters, glue or correctionfluid. The use of an approved scientific calculator is expected,where appropriate.You may lose marks if you do not show your workingor do not use appropriate units. Section A [45 marks]Answerallquestions.Write your answers in the spaces provided on the questionpaper. Section B [20 marks]Answer anytwoquestions. Write your answers in the spaces provided onthe question paper. At the end of the examination, fasten all your worksecurely together.The number of marks is given in brackets [ ] at theend of each question or part question.For Examiner’s Use Section A 45 Section B 20 TOTAL 65 1

Setter: Mr Adrian LimThis document consists of17printed pages includingthe cover page Section A: (45 marks)Answerallthe questions in the spaces provided 1 Two forces of magnitude 10.0 N and 14.0 N act on anobject,Pas shown in Fig 1.1. Fig 1.1 Using a suitable scale, draw a scale diagram to determinethe magnitude anddirection of the resultant force onP. 2

scale: 1 cm represents……..…………N [1] resultant force =……..…………N [2] direction =……..………………………..……… [1]2 Fig. 2.1 below shows an electric scooter used by Danial to travel from home toschool. He accelerates uniformly fromrest to2.5m/sin3.0s. Hecontinuesat thisspeed for 9.0 s on a straight horizontal path beforedecelerating uniformly in 5.0 s Fig. 2.1 (a) On Fig. 2.2, complete the graph to display the variationof speed of theelectric scooter with time. [2] 3

Fig. 2.2 (b) Calculate the average speed of the electric scooterfor the journey. average speed =……..…………m/s [2] (c) Calculate the deceleration of the scooter during thelast 5.0 s. [2] 4

deceleration =……..…………m/s 2 3 Fig. 3.1 shows a parachutist falling from the aircraft. Fig. 3.1 He is accelerating towards the Earth. (a) State his initial acceleration as he steps out ofthe aircraft acceleration =……..…………m/s 2 [1] (b) After he opened his parachute, theforcesactingonhimarerepresentedinasimplified diagram shown in Fig. 3.2. 5

Fig. 3.2 (i) Determine the resultant force acting on him. resultant force =……..…………N [1] (ii) Hence, calculate his deceleration. The parachutist has a mass of 80 kg. deceleration =……..…………m/s 2 [2] 4 Fig. 4.1 belowshows a hydraulic systemthat consistsof twopistonsandaflexiblepipe. The cross-sectional area of the smaller pistonis500cm 2 andcross-sectionalarea of the larger piston is 1440 cm 2 . Fig. 4.1 A force of 14 kN is exerted by the smaller pistonon the oil. (a) Calculate the pressure on the oil exerted by the small piston. [2] 6

pressure =……..…………N/cm 2 (b) The pressure on the oil by the smaller piston isthesameasthepressureofthe oil on the larger piston. Through thecalculationof theforces, showthat theforceonthelarger pistonis greater than the force by the smaller piston. [2]5 Fig. 5.1 shows a gymnast on a trampoline. At positionAinFig. 5.1a, thegymnaststartstorise. ShepassesthroughBinFig.5.1bandreacheshermaximumheightatC. Fig. 5.1a Fig. 5.1b (a) State the form of energy stored in the stretched springsshown in Fig. 5.1a. ……..…………………..………………………..……………………..…..…….. [1] (b) When the gymnast is at B, her kinetic energy is 1900 J, itsmaximumvalue.The mass of the gymnast is 45 kg. (i) Calculate the speed of the gymnast atB. [2] 7

speed =……..…………m/s (ii) Ignoring the effects of any friction and assuming the gravitationalacceleration is 10 m/s 2 , calculatethemaximumheight that thegymnastcan rise up to fromBtoC. height =……..…………m [2] 6 Fig. 6.1 shows howa baby’s milk bottle canbeheatedusingabottlewarmer. Thebottle warmer has foam-filledwallsandashinyouter casing. Heat isprovidedbya200Wheatingelement. Theheatingelement raisesthetemperatureof theliquidinthe warmer to 40 0 C. Fig. 6.1 (a) Describe and explain how the foam-filled walls andshiny outer casing reduceheat loss from the bottle warmer to the surroundings. (i) Foam-filled wall: ….…..………………………..…………………………….. ……..………………...…..……………………..……..…………………………. ……..…………………..………………………..………………...….…… [2] 8

(ii) Shiny outer casing: ……..………………………..…………………...……. ……..…………………..…………...……………..…………………………..…. ……..…………………..………………………..………………...……..... [2] (b) Whenthetoppartofthebottleisremoved,itisnoticedthatsomeofthemilk evaporates. Describeandexplain,usingideasaboutmolecules,whathappensduringevaporationandwhateffectdoesit haveonthetemperatureofthe remaining liquid. ……..…………………..………………………..……………………………....……… ……..…………………..………………………..……………………………………… ……..…………………..………………………..……………………….………...…… ……..…………………………..………………………..……………………...… [2] 7 (a) An object is placed 8 cm in front of a thin converginglens, as shown inFig. 7.1. Fig. 7.1. Fis the principal focus of the lens. 9

(a) On Fig. 7.1, draw rays from the top of the objectto determine the positionof the image. Mark the position of the image withthe letter I. [2] (b) The object is now moved so that it is now 40 cm fromthe lens. State three characteristics of the new image formed. ……..…………………..…...……………………..…………………………….……… ……..…………………………..………………………..…………...…………… [2] 8 In Fig. 8.1, short metal threads are attached to a metal ball. The metal ball andthreads contain negative charges that are free to move throughout the metal andpositivechargesthat arenot freetomove. Themetal rodandthreadhasnooverallcharge. Fig. 8.1 Fig. 8.2 In Fig. 8.2, a negatively charged rod is placed underthe metal ball and the metalthreads move away from the metal ball as shown. (a) Explain why the metal threads move away from the metal ball in Fig. 8.2 ……..…………………..…………………...…………..……………………….……… ……..…………………..…………………...…………..……………………….……… 10