Class 11 Physics Model Question and Solution: SET 2

Hey there, Class 11 students!
We've got something super exciting for you – the Class 11 Physics Model Question and Solution SET 2. Think of it as a treasure map to help you conquer the world of physics.
Physics is like the magic behind how things work – from tiny particles to big stars. Our SET 2 questions cover all kinds of cool stuff you're learning. Each question is like a little challenge, and solving them will make you a physics champ.
But here's the cool part – we're not leaving you hanging! We've also got the answers for you. And not just any answers – these are step-by-step solutions. So, it's like having a guide to show you how to crack the puzzle. You're not just finding answers; you're learning how to think like a physics whiz.

Disclaimer:
Answers might be all correct. I took help of book, search engines, and teachers to solve the set. However, the language or process of solving the questions might be informal and in examinations, you might have to add little more language and show more calculations than what has been done here.
I highly encourage you to view these solutions as guide rather than just copying everything mentioned here.

GROUP - A: Multiple Choice Questions [11×1=11]

Tick the correct answer.

1. A body is projected with velocity v1 from the point A

as shown in the figure. At the same time, another body

is projected vertically upwards from B with velocity v2.

The point B lies vertically below the highest point. For

both the bodies to collide, v2 v1 should be

a. 2 b. 0.5 c. d. 1

2. In a charged capacitor the energy resides:

a. On the positive plate b. On both positive & negative plates

c. In the field between the plates d. Around the edge of capacitor plates

3. Which of the following is always conserved in collision?

a. Kinetic energy b. Angular momentum

c. Linear momentum d. Torque

4. If the radius of earth were to decrease by 1%, its mass remaining the same, the

acceleration due to gravity on the surface of the earth will

a. increase by 1% b. decrease by 2%

c. decrease by 1% d. increase by 2%

5. If length of a wire is doubled keeping the diameter constant, its Young’s

modulus of elasticity will

a. increases b. decreases

c. remains same d. depends on nature of matter

6. A convex mirror of focal length 20cm produces an image 1 3 times the size of

the object. Then the distance in between the object and its image is

a. 40 cm b. cm c. cm d. None

7. Total internal reflection occur when the light passes

a. Denser to rarer b. Rarer to denser

c. The μ is same d. None

8. An object PQ is placed facing the hypotenuse of 45-90-45

glass prism. What is the nature of the image formed ?

a. Erect and diminished b. Erect and same size

c. Inverted and magnified d. Inverted and same size

9. The focal length of lens in air is 30 cm. Find the focal length of

the lens in water (Given, μw = 1.33 and μg = 1.5)

a. 120 cm b. 20 cm c. 90 cm d. 60 cm

10. The space around stationary charge has

a. Electric field only

b. Magnetic field only

c. Localised electric as well as magnetic field

d. Electric and magnetic fields that are radiated

11. When a body moves with a constant speed along a circle

a. No acceleration b. No force acts on the body

c. Velocity remains constant d. Work done is zero

GROUP – B: Short Answer Questions [8×5=40]

1. a. If two non-zero vectors are acted on a body, in what condition the resultant

vector on the body will be zero? [1]

b. A stone attached to a string is whirled round in a

horizontal circle with a constant speed of 10ms–1

.

Calculate the difference in the velocity when the stone is

(i) at opposite ends of a diameter (ii) in two positions A

and B where angle AOB is 90° and O is the centre of the

circle. Ans:20m/s, 14.14m/s [2]

c. What is the angle between velocity vector and acceleration

vector in uniform circular motion? Ans: 90o

[1]

OR

a. What sort of energy is associated with a bird flying in air ? [1]

b. Show that final kinetic energy of a body is equal to the sum of initial kinetic

energy and work done on the body. [3]

c. In a tug of war, one team is slowly giving way to other. What work is being

done and by whom? [1]

2. a. Which physical property of molecules of a gas gives a measure of

temperature? [1]

b. A steel wire 8m long and 4mm in diameter is fixed to two rigid supports.

Calculate the increase in tension when the temperature falls by 100C. Given

linear expansivity of steel, α = 12×10-6 /K, Young’s modulus for steel, Y = 2×1011 N/m2. Ans: 301.6N [3]

c. Does the coefficient of linear expansion depend on length? Explain. [1]

3. a. A tray containing 0.20 kg of water at 20 °C is placed in a freezer. (a) The

temperature of the water drops to 0 °C in 10 minutes.

(specific heat capacity of water = 4200 J kg - 1 K – 1) Calculate

(i) the energy lost by the water as it cools to 0 °C, [Ans: 1.68 × 104 J]

(ii) the average rate at which the water is losing energy, in J s–1. Ans: 28W [1+2]

b (i) Estimate the time taken for the water at 0 °C to turn completely into ice. [1]

(specific latent heat of fusion of water = 3.3 x 1 0 5J kg – 1) Ans: 2.36 × 103s

(ii) State any assumptions you make. [1]

[Hint: That there is a constant rate of heat loss .That the ice remains at 0oC ]

4. a. State two quantities which increase when the temperature of a

given mass of gas is increased at constant volume. [1]

[Hint : pressure of the gas and the (average) kinetic energy or rms speed]

b. A car tire of volume 1.0 × 10–2 m3 contains air at a pressure of 300 KPa and

a temperature of 290 K. The mass of one mole of air is 2.9 × 10–2 kg.

Assuming that the air behaves as an ideal gas, calculate [2]

(i) n, the amount in mol of air.

(ii) the mass of the air [1.2 mol, 10.036 kg]

c. Air contains oxygen and nitrogen molecules. State, with a reason, whether the

following are the same for oxygen and nitrogen molecules in air at a given

temperature.

(i) The average kinetic energy per molecule

(ii) The r.m.s. speed [2]

5. a. Explain, how does a convex lens produces a real image from virtual

object? [2]

b. A lens forms an image of an object. The object is 16.0 cm from the lens. The

image is 12.0 cm from the lens on the same sides as the object.

(i) What is the focal length of the lens? Is the lens converging or diverging?

(ii) If the object is 8.50 mm tall, how tall is the image. Is it erect or inverted?

(iii) Draw a ray diagram. [3]

[Ans: 48.0 cm, the lens is diverging, 0.6375 cm image virtual and erect ]

OR

a. "A concave mirror is called converging mirror. Why? [1]

b. State one daily application of a convex Mirror. [1]

c. A ray of light is incident at 60° in air on an air-glass plane surface. Find the

angle of refraction in the glass (μ for glass = 15). Ans: 35.3° [3]

6. a. If dielectrics is inserted between the charged capacitor, what will be

effects on the energy stored in the capacitors? [2]

b. A thundercloud and the earth can be regarded as a parallel plate capacitor.

Taking the area of the thundercloud to be 50 km2 , its height above the earth

as 1 Km and its potential as 100 KV, calculate the energy stored in it. [3] Ans: 2212.5J

7. a. Is it possible to have point where potential is zero but electric field is non

zero? Give an example. [2]

b. Three charges 1μC, 2μC, and 3μC are placed respectively at the corners

A, B, C of an equilateral triangle of side 1 metre. Calculate the potential

at a point which is half way along BC. [ε0 = 8.85 ×10-12 Fm-1] [3] Ans: 9.8 ×104V

8. a. What is one unit electricity? [1]

b. A 50 Ah battery can supply a current of 50A for 10 h. What total energy

can be supplied by a 12V, 60 Ah battery if its internal resistance is

negligible? [2] Ans: 2.6 × 104 J

c. Can terminal potential difference by greater than emf of a cell? [2]

GROUP – C: Long Answer Questions [3×8 = 24]

9. The graph shows a cyclist riding along a straight level road at a constant speed.

The graph below shows how the speed changes as the power output of the cyclist

changes.

a. i. Write down the equation that links power, time and work done. [1]

ii. Calculate the work done by the cyclist when his power output is 200 W for 1800 seconds. [2] Ans: 360 kJ 

b. Calculate the percentage increase in speed of the cyclist when the power output changes from 200 W to 300 W. [2] Ans: 16%

c. What is acceleration due to gravity? Explain how it varies with the altitude and depth. [3]

10. a. Derive an expression for the energy stored in a stretched wire. Define the

term energy density u of a body under strain. [3]

b. What is the percentage increase in the length of a wire of diameter 2.5 mm

stretched by a force of 100 kg? Young's modulus of elasticity of the

wire is 12.5 × 1011 dyne cm–2. [3] Ans: 0.16%

c. Iron is more elastic than rubber. Why? [2]

OR,

a. i. State the relationship between the gravitational potential energy, Ep and

the gravitational potential V for a body of mass m placed in a

gravitational field. [1]

ii. What is the effect if any, on the values of Ep and V if the mass m is

doubled? [2]

b. The diagram above shows two of the orbits, A and B, that could be occupied by a satellite in a circular orbit around the Earth, E. The gravitational potential due to the Earth of each of these orbits is: orbit A = – 12.0 MJ kg–1 and, orbit B = – 36.0MJ kg–1

(i) Calculate the radius from the centre of the Earth

of the orbit A. Ans: 3.3 × 107 m [1]

(ii) Show that the radius of orbit B is approximately 1.1×104 Km. [1]

(iii) Calculate the centripetal acceleration of a satellite in orbit B. Ans:3.2 ms-2[1]

(iv) Show that the gravitational potential energy of a 330 kg satellite decreases

by about 8 GJ (i. e. 8 × 109J) when it moves from orbit A to orbit B. [2]

11. a. Define atomic mass unit and convert it into MeV. [2]

b. The energy liberated in the fission of a single atom of uranium -235 is 3.2×10-11 J.

Calculate the power production corresponding to the fission of 1 gm of

uranium per day. (Assume Avogadro constant = 6.0 × 1023 mole-1). [3] Ans: 9.46 × 105 W

c. Distinguish between nuclear fusion and fission with examples. [3]