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SECOND PRELIM EXAMINATION 2015-16 STD: 10 Date: 16/1/16 Marks: 80 Dur: 2 hrs. Subject: Physics SECTION I (40 Marks) (All questions in this section are compulsory) Question 1:(a) A unit of a physical quantity is stated as kgm2s-2. Name and define the physical quantity. 2 (b) A train is travelling on level track at a speed of 72 km/h. It is pulled by an engine which exerts a force of 12000 N. Calculate the power of the engine in kilowatt. 2 (c) What are contact forces? Give an example. 2 (d) The hammer of an electric bell strikes 1440 times in a minute and does a work of 0.2 J per strike. What is the power of hammer in SI system? 2 (e) Sate two differences between a mechanical wave and electromagnetic wave. 2 Question 2 :(a) Explain why the bottom of the tank filled with water appears raised. (b) The handle of water pump 80 cm long has fulcrum at a distance of 15 cm from the load. If a load of 80 N is overcome, calculate the effort applied. (c) Why is the mechanical advantage of class 3 lever always less than 1. (d) When does a ray of light passing through a rectangular glass slab does not suffer refraction? What is the angle of incidence in such a situation? (e) Name a material whose resistance:i) Increases with rise in temperature ii) Remains unaffected with the rise in temperature. Question 3:(a) Complete the ray diagram below,( ic = 42 ) 2 2 2 2 2 2 45 87 (b) A wire of length 120 cm and area of cross section 0.2 cm 2 offers a resistance of 4 . Calculate the specific resistance of the wire. (c) Define the commercial unit of electrical energy. Express the unit in the S.I unit. (d) A bulb of resistance 400 glows brightly when connected to line voltage V. If the power of bulb is 100 W, calculate the value of V. (e) Calculate the heat energy required to convert 5 g of ice at 0 0 C to water at 00 C. (Specific latent heat of ice is 336 Jg-1, specific heat capacity of water is 4.2 Jkg-1 0C-1) Page 1 of 3 2 2 2 2
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