CBSE Class XI Physics sample paper 2008

http://www.cbseguess.com/-------------------------------------------------------------------------------------------------------www.cbseguess.com Other Educational Portals www.icseguess.com | www.ignouguess.com | www.dulife.com | www.magicsense.com SAMPLE PAPER -08 Class -XI Subject -Physics (Theory) Time: 3 hours Max. Marks 70 General Instructions 1. All questions are compulsory. Symbols have their usual meaning. 2. Q.No. 1 to 8 are of very short answer type questions, carrying 1 mark each. 3. Q.No.9 to 18 are of short answer type questions, carrying 2 marks each. 4. Q. No. 19 to 27 carry 3 marks each. 5. Q. No. 28 to 30 carry 5 marks each. 6. Use of calculator is not permitted. However you may use log table, if required. 7. Draw neat labelled diagram wherever necessary to explain your answer. 1. What does speedometer of a car indicates? 2. Write down the dimensions of viscosity coefficient. 3. What is the effect on viscosity of gases when temperature is increased? 4. A light body and heavy body have equal momentum, which one have greater kinetic energy? 5. Why do we use ball –bearings? 6. State Newton’s universal law of gravitation and express it in vector form. 7. Calculate the moment of inertia of a uniform ring of mass 500 g and radius 10 cm, about its diameter. 8. What would be the excess pressure inside a water bubble of radius 0.2 mm? Surface tension of water at020C is 0.72 X 110 N/m 9. How errors are combine in following mathematical operations of physical quantities? i) Subtraction ii) Product 10. Draw the Velocity – Time graph for following cases when i) Object is moving in positive direction with acceleration ii) An object is under free fall 11. Find the torque of a force 7i+3j-5k about the origin. The force acts on a particle whose position vector is i-j +k. 12. Derive the necessary relation for safest velocity of an automobile on a banked road of radius r and friction coefficient . http://www.cbseguess.com/-------------------------------------------------------------------------------------------------------www.cbseguess.com Other Educational Portals www.icseguess.com | www.ignouguess.com | www.dulife.com | www.magicsense.com 13. The escape velocity (v) of a body depends upon the mass (m) of body, gravitational acceleration (g) and radius(R) of the planet .Derive the relation for escape velocity dimensionally. 14. State and Prove Work-Energy Theorem. 15. Derive the necessary relation for orbital velocity of a satellite and prove that 23TR using it. 16. What do you mean by positive, negative and Zero work done .Give at least one example of each case. OR Prove that mechanical energy remains conserved during motion when a body of mass m is dropped from a height h. 17. Two masses 8 kg and 12 kg are connected at the two ends of an inextensible string that passes over a frictionless pulley. Find the acceleration of the masses and tension in the string when masses are released. 18. Two bodies of masses 12mandm (12mm), moving with initial velocities 12uandu12()uu, along a straight line in the same direction, suffer perfect head on collision. Find their velocities after collision. 19. State Hooke’s law. Explain Stress – Strain curve of a material when subjected under extended load. 20. State Parallelogram law of vector addition. Find the magnitude and direction of the resultant of two vectors A and B in terms of their magnitudes and angle between them. 21. Explain following with proper reason (any two) a) Why blood pressure in humans is greater at the feet than at brain. b) Water wets the glass surface while mercury does not. c) The dome of water reservoir thick at bottom. 22. What do you mean by acceleration due to gravity? What are the factors affect the value of g ? Derive the necessary relation for variation of g with depth. 23. State Stokes’ law and derive the expression for critical velocity in case of a sphere falling through a viscous fluid like Glycerine. 24. Suggest some ways to minimize friction. OR Explain why it is easier to pull a roller than to push it. http://www.cbseguess.com/-------------------------------------------------------------------------------------------------------www.cbseguess.com Other Educational Portals www.icseguess.com | www.ignouguess.com | www.dulife.com | www.magicsense.com 25. State Newton’s laws of motion with at least one example of each. 26. Define Centre of mass. A body projected into space explodes. What will be the nature of path of its core? 27. If Earth were suddenly shrink to ½ of its present radius without change in mass, what is the effect on duration of day? 28. a) Derive the equation S = ut + ½ 2at using graphical method. b) A ball is thrown vertically upward with a velocity 20 m/s from the top of a multistory building. The height of the point from where the ball is thrown is 25 m from the ground, i) How high the ball rise? ii) With what velocity strike the ground? OR A projectile is fired in air making an angle with horizontal. Show that i) Its path is parabolic in nature. ii) tan = 4H /R where H is maximum height attained and R is the range of projectile. 29. a) Three bodies a ring, a solid cylinder and a solid sphere, having identical radius, roll down the same inclined plane without slipping .They start from rest. Which of the three reaches the ground with? i) Maximum velocity ii) minimum velocity b) State Theorem of Parallel Axes. OR a) State and prove Angular momentum Conservation principle. b) Explain how an acrobat in circus takes advantage of it. 30. a) State Pascal’s law. How it can be used in Hydraulic lift. b) The density of the atmosphere at sea level is 1.3 kg /3m. Assume that it does not change with altitude, then how high would the atmosphere extend? OR State and prove Bernoulli’s theorem. Explain any one application of it.