CBSE Board Class 11 Physics Previous Year Question Papers 2009

Previous Paper 2009
Class   - XI
Subject - Physics (Theory)
Time:    3 hours          Max. Marks   70
General Instructions
1. All questions are compulsory. Symbols have their usual meaning.
2. Use of calculator is not permitted. However you may use log table, if required.
3. Draw neat labelled diagram wherever   necessary to explain your answer.
4. Q.No. 1 to 8 are of very short answer type questions, carrying 1 mark each.
5. Q.No.9 to 18 are of short answer type questions, carrying 2 marks each.
6. Q. No. 19 to 27 carry 3 marks each.  Q. No. 28 to 30 carry 5 marks each.
                                                       
1. What is the ratio of A.B to A X B  when angle between A and B is 600?

2. Write down the dimensions of universal gravitation constant .

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. Two absolute scales A and B have triple points of water defined to be 275 A and
       50 B. What is the relation between TA  and TB .

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 200 g and radius 
20 cm, about one of its tangent which is perpendicular to the plane of ring.

8. What would be the excess pressure inside a mercury drop of radius 0.8 mm?
Surface tension of mercury at 200 C is  465 X 10 3 N/m 

9. A physical quantity P is related to four observables a,b,c and d as follows ;                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              
     P = √ab
      The percentage errors in a,b,c and d are 2%, 4% ,3% and   
      2% respectively. What is  the percentage  error in the quantity P .

10. Draw   the Velocity   – Time graph for following cases when 
     ( i) Object is moving  with  positive  acceleration  ( ii)  An object is under free fall

11.  Explain following with proper reason.
      (a) Why blood pressure in humans is greater at the feet than at brain.          
(b) Water wets the glass surface while mercury does not.       

12. Derive the necessary relation for safest velocity of an automobile on a banked
             road of  radius r and friction coefficient  .

13. Explain with reason Why:
     (a)  A brass tumbler feels much colder than a wooden tray on a chilly day.
(b) The earth without its atmosphere would be inhospitably cold.

14. State and Prove Work- Energy Theorem for variable force case.
      OR
    What do you mean by conservative and  non conservative force. Give  one 
      example of each case.

15. Derive the necessary relation for orbital velocity of a satellite and prove that 
T2R 3 using it.

16.  The Energy of a body executing SHM depends on the mass m, its frequency f
        and amplitude a. Derive the relation for energy using dimension methos.

17. State Hooke’s law.  Explain Stress – Strain curve of a material when subjected  
       under   extended load.

18. A body of mass  m 1  moving with velocity  u 1 along a straight line collide with  
                   another  body  of  mass m2 , perfect elastically, which is initially at rest. . Find
                   their velocities after collision.

19. What do you mean by acceleration due to gravity? Derive the necessary relation   
       for variation of g with depth.

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. 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.

22. Define molar specific heat capacities at constant volume and pressure. Show that        
     CP - CV= R. Where Symbols have their usual meaning.

23. State Stokes’ law and derive the expression for critical velocity in case of a small  
      Spherical body  falling through a viscous fluid like Glycerine.

24. State Pascal’s law. How it can be used in Hydraulic lift.

25. (a) Three bodies of identical radii ,a ring a solid sphere and a solid cylinder roll down the same  inclined plane without slipping. They start from rest. Which 
             of the bodies reaches the ground with maximum velocity ?
      (b) State the Parallel Axes theorem  of  moment of inertia.
OR
(a) A metal bar 70 cm long and 4 kg in mass supported on two knife edges placed
10 cm from each end. A 6 kg load is suspended at 30 cm from one end. Find the
reactions at the knife edges. Assume the bar to be of uniform cross section and
homogeneous.
 (b) State the theorem of perpendicular axes of moment of inertia.

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)   What is angle of contact? When it is obtuse ? When it is acute?
   ( b) Show that excess pressure inside a drop of radius r is Pi – Po = 2S /R .
                                                               OR
                State and prove Bernoulli’s theorem. Explain any one application of it.

29.  Answer any three from following.
      (a) Suggest some ways to minimize friction.                           
(b) Explain why it is easier to pull a roller than to push it.
     (c)  A constant force acting on a body of mass 3 kg changes its speed from 2 ms
-1
               
to 3.5 ms
-1
in 25 s. The direction of the motion of the body remains   
          unchanged. What is the magnitude and direction of the force.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   
    OR
(a) Passengers are thrown forward from their seats when a speeding bus stops
suddenly.   (b) A cricketer moves his hands backwards while holding a catch.
(b) An aircraft executes a horizontal loop at a speed of 720 km/h with its wings   
banked at 15
0
. What is  the radius of the loop.

30.  (a) Derive the equation v
       (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)  A projectile is fired in air making an angle   with horizontal. Show that
          (i) Its path is parabolic in nature.   (ii) tan ɵ  = 4H / R where H is 
           maximum height   attained and R is the range   of projectile.
(b) An aircraft executes a horizontal loop of radius 1.00 km with a steady speed  
          of  900 km/h. Compare its centripetal acceleration with the acceleration due to
         gravity.