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Cal LOKHANDWALA FOUNDATION SCHOOL PRELIMINARY EXAMINATION - 2020-21 SUBJECT: PHYSICS Date : 15/01/2021 Duration: 2 hrs Grade: 10 Max Marks: 80 __________________________________________________________________________________ General Instructions: This question paper consists of two sections A and B. Section A is compulsory. Attempt any four questions from Section B. This paper consists of 4 printed sides. __________________________________________________________________________________ SECTION A (40 marks) (Attempt all questions from this section) Question 1 a) In a uniform circular motion, the body moves with uniform acceleration. Is this statement true? Explain your answer. (2) b) How much work is needed to be done on a ball of mass 100 g to give it a momentum of 5 kg m/s ? (2) c) A radioactive substance is oxidized. How would the nature of radioactivity be changed ? Explain your answer. (2) d) Name the constituent colour of white light for which i) the deviation produced by the glass prism is the least . ii) the refractive index of glass is maximum. (2) e) State two differences between Forced and Resonant vibrations. (2) Question 2 a) Calculate the power of an engine required to lift 100 kg of coal per hour from a mine 360 m deep ? (Take g= 10 m/s ). (2) b) Name a simple machine which can be used to : i) multiply force ii) only change the direction of force applied. (2) c) 2000 calories of heat is supplied to 100 g of water. Find the rise in temperature. (Take specific heat capacity of water as 1 cal g C .) (2) d) Which is easier to turn: A steering wheel of a large diameter or a steering wheel of a small diameter ? Explain your answer. (2) e) A ray of light enters a glass slab as shown in the figure below. Copy and complete the path of the ray till it emerges out from the slab. Mark the necessary angles in the diagram . (2) Question 3 a) State the conditions required for the total internal reflection of light to take place. (2) P.T.O
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