52_Crescent 2013 P2_Ans (1)

This paper consists of 11 printed pages (including the cover page), and 3 lined pages. CRESCENT GIRLS’ SCHOOL SECONDARY FOUR PRELIM EXAMINATION PHYSICS 5058/02 Paper 2 28 Aug 2013 1 hr 45 min Class: Register No: Name: MS READ THESE INSTRUCTIONS FIRST Write your name, index number and class in the spaces provided at the top of this page and on all separate answer sheets used. Write in dark blue or black pen. You may use a soft pencil for any diagrams, graphs, tables or rough working. Do not use staples, paper clips, highlighters, glue or correction fluids. Section A (50 marks) Answer all questions. Write your answers in the spaces provided on the question paper. Section B (30 marks) Answer all questions. Question 11 has a choice of parts, answer either one. Write your answers in the writing paper provided. At the end of the examination, fasten all your work securely together. The number of marks is given in brackets [ ] at the end of each question or part question. Unless specified in the question, you may assume the following constants: Gravitational acceleration = 10 ms-2 Speed of light in vacuum = 3  108 ms-1 For Examiner’s Use Section A /50 Section B /30 TOTAL

2 13 5058 S4 Prelim Section A (50 marks) Answer all questions. Write your answers in the spaces provided in the question paper. 1. The figure shows a windsurfer A in equilibrium with a wind force acting on the sail of his board. The weight of the windsurfer is 700 N. a) State the principle of moments that applies to a body in equilibrium. [1] When an object is in equilibrium, the sum of clockwise moments about any point is equal to the sum of anticlockwise moments about the same point. b) Calculate the moment exerted by the weight of the windsurfer about the pivot P. [1] Moment = Force x perpendicular distance = 700 x 0.5 = 350 Nm [1] _________________________________________________________________________ c) Calculate the force of the wind on the sail. [2] Taking moment about pivot P, Clockwise moments = Anti-clockwise moments Wind Force x 1.4 = 700 x 0.5 [1] Wind Force = 250 N [1] _________________________________________________________________________ d) Explain why the windsurfer must lean out more if the wind speed increases. [2] As the wind speed increases, there is a greater force on sail. AND/OR a greater clockwise moment is generated by the wind. [1] Hence a greater anticlockwise moment is required. A greater perpendicular distance of the windsurfer (from pivot) is required to balance the greater clockwise moment from wind. [1] e) If windsurfer B with a greater mass trie