42_SMSS Prelim 2011 P2

Name: …………………………………….……….. Reg. No. ………… Class: ………….… Secondary 4 Express 15th September 2011 Duration : 1 hour 45 minutes Total Marks : 80 READ THESE INSTRUCTIONS FIRST Do not open this Booklet until you are told to do so. Write your name, register number and class in the spaces at the top of this page and on any separate writing paper used. Write in dark blue or black pen. You may use a soft pencil for any diagrams, graphs or rough working. Do not use staples, paper clips, highlighters, glue or correction fluid. Section A Answer all questions. Section B Answer all questions. Question 13 has a choice of parts to answer. Write your answers to Section A and to Questions 10,11 and 12 in the spaces provided on the Question Paper. Write your answer to Question 13 on the lined pages and, if necessary, continue on the separate Answer Paper provided. At the end of the examination, fasten all your work securely together. Candidates are reminded that all quantitative answers should include appropriate units. Candidates are advised to show all their working in a clear and orderly manner, as more marks are awarded for sound use of physics than for correct answers. The number of marks is given in brackets [ ] at the end of each question or part question. When necessary, assume the acceleration due to gravity, g to be 10 m/s2. ________________________________________________________________________ This question paper consists of 20 printed pages PHYSICS 5058/02 St. Margaret’s Secondary School Preliminary Examinations 2011 [Turn over

2 Section A Answer all the questions in this section. 1 A police driving test concluded that Sarah has a reaction time of 0.5 s. It was also tested that her car had a deceleration of 5.0 m/s2. a) Sketch the speed-time graph at the instance when she sees the traffic light turning red, assuming that she has to bring her car to rest from the speed of 10 m/s. [2] b) Determine the distance she travelled from seeing the traffic light turning red till it comes to rest from the speed of 10m/s. [2] 2 In May 2006, Singapore first Helium ride, the DHL balloon was launched. Figure 2 shows the schematic diagram of the balloon. The weight of the balloon is 4200 N. The speed at which the balloon drifts up can be controlled by a cable attached to the balloon. The balloon is lifted up by an upthrust created due to the density of helium gas. This upthrust is constant throughout the motion of the balloon. Fig. 2 a) On figure 2, draw and label the arrow to shows the direction of the forces experienced by the balloon. [3] Cable which attacheds the balloon to the ground.

3 b) Find the tension in the cable when the balloon is moving up at constant speed, given that the upthrust is 4800 N. Explain your working clear