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First Preliminary Examination 2020-2021 Physics Grade: 10 Date: 16/12/20 Max. Marks:80 Time Allowed: 2 hours INSTRUCTIONS: Answers to this paper must be written on the paper provided separately. You will not be allowed to write during the first 15 minutes. This time is to be spent in reading the question paper. The time given at the head of this paper is the time allowed for writing the answers. The intended marks for the questions or parts of questions are given alongside the questions. Attempt all questions from Section I. Attempt any four questions from Section II. SECTION I (40 marks) Attempt all the questions from this section Question 1 a. What do you understand by moment of force? Give one way to obtain a greater moment of force about a given axis of rotation. b. A boy weighing 50kgf climbs up a stair of 20 steps each 20cm high in 4min and a girl weighing 30 kgf does the same in 2min ,compare (i) The work done by them and (ii) The power developed by them . c. Explain the term Mechanical Advantage. Why M.A V .R for an actual machine. d. What do you mean by the following statement ? (i) The heat capacity of a body is 50 J K 1 ? (ii)The specific heat capacity of copper is 0.4 J g 1 k 1 ? e. A metal piece of mass 50g at 270 C requires 2400 J of heat energy in order to raise its temperature to 3270 C . Calculate the specific heat capacity of the metal. [2] [2] [2] [2] [2] Question 2 a. i) State the effect of presence of impurity on the melting point of ice. ii) State the effect of increase of pressure on the melting point of ice. b. An electromagnetic radiation is used for photography in fog i) Identify the radiation. ii) Why is this radiation mentioned by you ideal for this purpose? 1 [2] [2]
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