Class- XI

                                                                                             Sample paper - 2

General Instructions:

1. All questions are compulsory. There are 37 questions in all.
2. This question paper has 4 sections: Section-A, Section-B, Section-C & Section-D.
3. Section A contains 20 questions of one mark.
4. Section-B contain 7 questions of 2 marks.
5. Section-C contains 7 questions of 3 marks
6. Section- D contains 3 questions of 5 marks each.
7. There is no overall choice.
8. Use of calculators is not permitted. However, you may use log tables if necessary.

SECTION - A

Question 1:                                                                                                                         

Name the type of substances that are known to be as elastomers. Give one example.

 

Question 2:                                                                                                                           

Young modulus of steel is 1.9 × 10¹¹ N/m². When expresses in CGS units of dynes/cm², it will be equal to (1N = 10⁵ dyne, 1m²= 10⁴ cm²)

 

Question 3:                                                                                                              

The displacement- time graph of two moving particles make angles 30⁰ & 45⁰ with x- axis. Find the ratio of their velocities.

 

Question 4:                                                                                                                           

The two row boats on sailing parallel and close to each other, experience a force which pulls them towards each other. Explain the reason for this statement.

 

Question 5:                                                                                                              

Why does the cricket player lower his hands while catching a ball?

 

Question 6:                                                                                 

Why is ‘invar’ is used for making the pendulum of the clock?

 

Question 7:                                                                                                                          

What is the degree of freedom of a monoatomic gas?

 

Question 8:                                                                                                              

The earth moving round the sun in a circular orbit is acted upon by a force and hence work must be done on the earth by this force. Do you agree with this statement?

 

Question 9:                                                                                                              

Why does small bubble have excess of pressure?

                                             OR

Define Random error?

 

Question 10:                                                                                                                           

Given below the graph of stress- strain graph for two materials A & B.

    (i) Which material has greater Young’s modulus

    (ii) Which of the two is the stronger material.

       

Question 11:                                                                                                                           

Why is mercury used in thermometer?

 

Question 12:                                                                                                                           

Give one example of natural and forced convection.

                                        OR

Under what condition will the direction of sum and difference of two vectors be same?

 

Question 13:                                                                                                                           

State the Kelvin-Planck’s statement of second law of thermodynamics.

Question 14:                                                                                                                           

What does the area of the shaded portion of the graph represent?

 

Question 15:                                                                                                                          

State the following statement is true or false.

In an elastic collision of two bodies, the momentum an energy of each body is conserved.

 

Question 16:                                                                                                                            

The blood pressure in humans is greater at the feet than at the brain. Explain the reason.

 

Question 17:                                                                                                                            

A body with large reflectivity is a poor emitter. Explain why?

 

Question 18:                                                                                                                            

The acceleration due to gravity on the surface of moon is 1.7 m/s². What is the time period of a simple pendulum on the surface of moon if its time period on the surface of earth is 3.5 s? (g on the surface of earth is 9.8 m/s²)

 

Question 19:                                                                                                                   

Will the momentum remain constant if some external force acts on the system?

 

Question 20:                                                                                                            

Give an example to show that the direction of velocity of a body can change even when its acceleration is constant.

 

SECTION - B

Question 21:

A body of mass 5 kg is acted upon by two perpendicular forces of magnitude 8 N and 6 N. Find the magnitude and direction of the acceleration.

 

Question 22:                                                                                                                            

Explain very briefly:

     (i) A horse cannot pull a cart and run-in empty space.

(ii) Passengers are thrown outward when a moving bus takes a sudden turn.

 

Question 23:                                                                                                                            

In dealing with motion of projectile in air, we ignore effect of air resistance on motion. This gives trajectory as a parabola as you have studies. What should be the trajectory look like if air resistance is included? Sketch such a trajectory and explain why you have drawn it that way.

 

Question 24:                                                                                                                            

What is the moment of inertia of a ring about a tangent to the circle of the ring?

                                                          OR

Why does gun recoils on being fired?

 

Question 25:                                                                                                                            

Three equal masses of m kg each are fixed at the vertices of an equilateral triangle ABC.

(a) What is the force acting on a mass 2m placed at the centroid G of the triangle?

(b) What is the force if the mass at the vertex A is doubled? Take AG = BG = CG = 1 m

 

Question 26:                                                                                                                    

Two masses of 5 kg and 3 kg are suspended with the help of massless inextensible strings as shown in fig. Calculate T₁ & T₂ when whole system is going upwards with acceleration =2 m/s² (use g= 9.8 m/s²).

 

Question 27:                                                                                                                            

If the angular momentum is conserved in a system whose moment of inertia is decreased. Will its rotational kinetic energy be also conserved?

OR

What do you understand by angle of repose? Derive its relation with angle of friction.

 

SECTION - C

Question 28:                                                                                                                            

It is easier to pull a lawn roller than to push it. Explain using the resolution of forces.

 

Question 29:                                                                                                                            

 A LASER is source of very intense, monochromatic, and unidirectional beam of light. These properties of a laser light can be exploited to measure long distances. The distance of the Moon from the Earth has been already determined very precisely using a laser as a source of light. A laser light beamed at the Moon takes 2.56 s to return after reflection at the Moon’s surface. How much is the radius of the lunar orbit around the Earth?

 

Question 30:                                                                                                                            

Oil spreads over the surface of water, whereas water does not spread over the surface of oil. Why?

 

Question 31:                                                                                                                            

State the main features of kinetic energy of an ideal gas.

 

Question 32:                                                                                                                            

Give reasons of the following:

    (a) A load on a thief’s back does not apply any force on him when he jumps from the upper story of a house.

    (b) A man falling from a height receives more injury when he falls on cemented floor rather than when he falls                on a heap of sand.

 

Question 33:                                                                                                                           

A balloon has 5 g mole of helium at 7° C. Calculate

    (a) The number of atoms of helium in the balloon.

    (b) The total internal energy of the system.

 

Question 34:                                                                                                                           

Two trains A and B of length 400 m each are moving on two parallel tracks with a uniform speed of 72 km/hr in the same direction, with A ahead of B. The driver of B decides to overtake A and accelerates by 1 m/s². If after 50 s, the guard of B just brushes past the driver of A, what was the original distance between them?

 

SECTION - D

Question 35:                                                                                                                           

The difference between the length of a certain brass rod and that of steel rod is claimed to be constant at all temperatures. Is it possible?

OR

A thin circular loop of radius R rotates about its vertical diameter with an angular frequency ω. Show that a small bead on the wire loop remains at its lower most point for ω ≤ g/R​. What is the angle made by the radius vector joining the centre to the bead with the vertical downward direction for ω=2g/R​? Neglect friction.

 

Question 36:                                                                                                                           

What do you understand by laminar flow or streamlined flow? Water is flowing with a speed of 2 m/s in a horizontal pipe with cross-sectional area 2 × 10^-2 m² at pressure 4 × 10⁴ Pa. What will be the pressure at a smaller cross-sectional where the area decreases to 0.01 m²?

 

Question 37:                                                                                                                           

    (a) If c is the r.m.s speed of molecules in a gas and ʋ is the speed of sound waves in the gas, show that c/ ʋ is         the constant and independent of temperature for all diatomic gases.

   (b) At what temperature is the root mean square speed of an atom in an argon gas cylinder equal to the rms              speed of a helium gas atom at – 20 °C? (atomic mass of Ar = 39.9 u, of He = 4.0 u).

OR

Figure shows a man standing stationary with respect to a horizontal conveyor belt that is accelerating with 1 ms^-2. What is the net force on the man? If the coefficient of static friction, between the man’s shoes and the belt is 0.2, up to what acceleration of the belt can the man continue to be stationary relative to the belt? (Mass of the man = 65 kg.)

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