# CBSE Board Class 11 Physics Previous Year Question Papers 2007

## CBSE Board Previous Year Question Papers 2007 for Class 11 Physics

Previous Paper – 2007

Class – XI

Subject - Physics

TIME: 3hr. MM: 70

General Instructions.

1. Questions from question no. 1-8 carry 1marks each, 9-18 carry 2 marks each, 19-27 carry 3 marks each and 28-30 carry 5 marks each.

2. There is no overall choice but one choice is given in 2 marks question, two choice in 3 marks question and all three choices in five marks question

3. You may use the following physical constant where ever necessary:
Speed of light C = 3 x 108 ms-1

Gravitational constant G= 6.6 x 10-11 NM2 Kg-2

Gas constant R= 8.314 J Mol-1 k-1

Mass of electron = 9.110 x 10-31 Kg

Mechanical equivalent of heat = 4.185 J Cal-1

Standard atmospheric pressure = 1.013 x 105 Pa

Absolute zero 0k = - 273.150c

Acceleration due to gravity = 9.8 Ms-2

1. If a composite physical quantity in terms of moment of inertia I, force F, velocity V,
work W and length L is defined as,
Q = (I F V2 /WL3)

Find the dimension of Q and identify it.

2. Explain why a man who fall from a height on a cemented floor receive more injury
then when he fall from the same height on the heap of sand.

3. Is it possible to have a collision in which all the kinetic energy is lost? If so cite an example.

4. You are given two spheres of the same mass, size and appearance, but one of them is solid while the other hollow. If they are allowed to roll down an incline which
One will reach the bottom first?

5. Can every oscillatory motion be treated as simple harmonic motion in the limit of small amplitude?

6. If the earth be at one half its present distance from the sun how many days will their be in a year?

7. A 25 cm long tube closed at one end is lowered with his open end down into a fresh water lake. If one- third of the tube is filled with water then what is the distance between the surface of lake and level of water in the tube.

8. Why zeroth law of thermodyamics is not called as IIIrd law though it was discovered after I and II law?

9. Define uniform velocity of an object moving along a straight line. What will be shape of velocity time and position time graphs of such a motion?

10. What do you mean by a projectile? A projectile is fired with velocity v making an angle Ө with the horizontal. Show that its path is parabolic.

11. Define the term momentum and impulse also derives the relation between them.

12. Define and explain moment of inertia of a rigid body about an axis of rotation. Hence define radius of gyration.

13. What do understand by gravitational field and gravitational field intensity? Show that acceleration due to gravity is a measure of the gravitational field of earth at a point.

OR

Define escape velocity. Derive an expression for escape velocity of an object from

the surface of a planet.

14. State newton’s law of cooling. Deduce the relation
log (Ө- Ө0) = - k t + c

15. In a refrigerator, heat from inside at 277K is transferred to a room at 300K. How many joule of heat will be delivered to the room for each joule of electrical energy consumed ideally?

16. Give the essential features of the kinetic theory of gases. Show that the pressure exerted by a gas is equal to two-thirds the of the average kinetic energy per unit volume of the gas molecule.

17. State Newton’s formula for velocity of sound in gases. Discuss Laplace correction. What is the effect of density and pressure and temperature on velocity of sound in air? Explain.

18. What are centripetal acceleration and centripital force? Derive expression for them.

19. What is elastic collision? Calculate the velocities of the two bodies undergoing elastic collision in one dimension.

20. Show that the acceleration of free fall g at the surface of earth and the gravitational constant G are related by the expression

g = 4\3 Π p G R,

21. State the conditions, which are necessary for a satellite to appear stationary. Show
how an satellite orbiting round earth obey Kepler’s third law.

22. Find the maximum length of a steel wire that can hang without breaking.
Given that breaking stress for steel = 7.9 x 1011 N M-2 and density of steel =7.9 x
103 Kg M-3

OR

Define young’s modulus of elasticity, normal stress and longitudinal strain. Give
units of each of them. Derive elastic potential energy of a wire when stretched.

23. The weight of a body in water is one third of its weight in air. What is the density
Of the material of the body.

OR

What is stokes law? Explain terminal velocity and mention its importance

24. Show that for a carnot engine, efficiency of the engine is >
η = 1- T2/T1 (T2 > T1)
Where T1 is the temperature of the source and T2 is the temperature of the sink.

25. If the orbital velocity of moon is increased by 42% than what will happen to its
position? Explain.

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