Central Board of Secondary Education (CBSE)

**Sample Paper – 2012
**

**Class – XI**

Subject –

Subject –

**Physics**

1) Write equation of S.H.M. having following characteristics:

Amplitude=0.01 m, frequency=600 Hz, initial phase=30^{o}

2) Round off the two significant figures add 8.2 and 10.163 and

3) How does soap help us to remove dirt better in washing clothes?

4) Velocity of a projectile is 10 ms^{-1}. At what angle of the horizontal should it be projected so that it covers maximum horizontal distance?

5) What is more elastic, water or air, why?

6) What is the displacement in an oscillating, when its velocity is 0.25 of its maximum velocity?

7) When all other condition remains same, which gas monotonic or a diatomic will permit sound to travel faster?

8) Can two nonzero vectors give zero resultant when they multiply with each other? If yes, give condition for same.

9) Give reason. Two sound source produce 12 beats in four seconds. By how much do their frequencies differ?

OR

What is difference between conservative and non conservative forces. Explain with one example each.

10) How can you say uniform circular motion is a variable accelerated motion.

11) Find the work done in moving a particle along a vector S=4i-j+7k. If the applied force is F= i+2j –kNewton. S is in meter.

12) Write the explanation about the triangulation method for measuring the inaccessible large distance (heights).

13) Represent graphically the variation of extension with load in an elastic body on the graph mark:

(a) Breaking point. (b)Yield point, (c) Elastic limit, (d) Hooke’s law region

14) Kinetic energy of a particle is increased by 300℅. Find the percentage increase in momentum.

15) What is work done by centripetal force? Explain.

16) A man is moving in rain hold his umbrella inclined to the vertical even through the rain drops are falling vertically downwards. Why?

17) The maximum acceleration of a simple harmonic oscillator is a_{o} and the maximum velocity is v_{o}. What is the displacement amplitude?

18) Calculate the power developed by a person while eating 100 g of ice per minute. Latent heat of ice= 80 cal/g.

19) A cricket ball of mass 150 grams moving with a speed of 12 ms^{-1 }is hit by a bat so that ball is turned back with a velocity of 12 ms^{-1}. Calculate the impulse received by the ball.

20) Assuming that the frequency of vibration (ν) of a stretched string depends upon the load applied (T), length of the string (l), and its mass per unit length (p), prove that

………….

21) Establish the relation between torque and angular acceleration. Hence define moment of inertia

OR

Establish the following relation: (i)……… (ii) ……………. (iii)………….

22) The string of pendulum is 2.0 m long. The body is pulled sideways so that the string becomes horizontal and the bob is released. What is the speed with which the bob is released? What is the speed with which the bob arrives the lowest point? Assume that 10℅ of initial energy is used against the air resistance. (g=10 m/s^{2})

23) Define escape velocity. Drive an expression for escape velocity of an object from the surface of planet.

24) Find an expression for the total energy of a body vibrating simple harmonically.

25) Name three type of basic forces in nature and briefly discus their characteristics.

26) How can we give expression for the excess of pressure inside a soap bubble.

27) Drive an expression for the distance traveled by a uniformly accelerated body in t seconds. Also drive an expression for the distance traveled by the body in the nth second.

28) Two wires, one of steel and other of aluminium, each 2 m long and of diameter 2 mm, are joined end to end to form composite wire of length 4 m. What tension in the wire will produced a total extension of 0.90 mm?

OR

Write your explanation about basic assumptions of kinetic theory of gases? On their basis drive an expression for the pressure exerted by an ideal gas.

Y for steel=2×10^{11} N/m^{2}; Y for aluminium= 7×10^{11} N/m^{2}

29) A steel tube whose coefficient of linear expansion is 18x 10^{-6}/^{o}C, contain Hg whose γ=180×10^{-6}/^{o}C.The volume of mercury contained in a tube is 10-^{5}m^{3} at 0^{o}C and it is desired that the length of mercury column should remains constant at all normal temperatures. This is achieved by inserting into the mercury column a rod of silica, whose thermal expansion is negligible. Calculate the volume of silica rod.

OR

A Carnot engine is working between source temperature of 500 K and sink temperature of 375 K. If the engine extracts 600kcal per cycle from the source, calculate

(a) Work done per cycle.

(b) When will the efficiency be 100 ℅.

(c) The efficiency of the engine

(d) Heat rejected per cycle to the sink.

30) The equation of plane progressive wave is given by:

ξ= 0.25 x 10^{-3 }sin (500t – 0.025x), Where ξ and x are in cm and t in seconds.

Calculate the amplitude, period, angular frequency, wavelength, amplitude of particle velocity.

OR

A man standing in front of a mountain at a certain distance beats a drum at regular intervals. The drumming rate is gradually increased, and he find that echo is not heard distinctly, when the rate becomes 40 per minute. He then moves nearer to the mountain by 90 meters, and find that echo is again not heard when the drumming rate is 60 per minute, calculate

(i) The distance between mountain and the initial position of the man

(ii) The velocity of sound.