PHYSICS Assessment-II (January 25, 2019) Subject: Physics Class: IX Name: _______________ Total Marks: 63 Subjective Part Date: ______________ Q No (1): Answers the following question. (Attempt all) 1) 2) 3) 4) 5) 6) 7) 8) 9) 10) 11) 12) 13) 14) 15) What is meant by the force of gravitation? Explain, what is meant by gravitational field strength? Can you determine the mass of our moon? If yes, then what you need to know? Define work. What is its SI unit? Define K.E. and derive its relation? Why fossils fuels are called nonrenewable form of energy? Name a device that converts mechanical energy into electrical energy? What is meant by the efficiency of a system & How can you find it? State Pascal's law? Why does a piece of stone sink in water but a ship with a huge weight floats? Define the terms heat and temperature? What is a thermometer? Why mercury is preferred as a thermometric substance? Explain conduction, convection and radiation? What is greenhouse effect? Explain the impact of greenhouse effect in global warming? Note: Attempt any THREE (3) questions. (3×7=21) Q No (2): a). Derive the expression for ‘‘THE MASS OF THE EARTH’’? b). Calculate the value of g, the acceleration due to gravity at an altitude 1000 km. The mass of the Earth is 24 6.0 x 10 kg. The radius of the Earth is 6400 km. Derive the expression for ‘‘THE MASS OF THE EARTH’’? Q No (3): a). A 50 kg man moved 25 steps up in 20 seconds. Find his power, if each step is 16 cm high. b). A brass rod is 1 m long at 0°C. Find its length at 30°C. -5 -1 (Coefficient of linear expansion of brass =1.9x10 K).