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## Karnataka 1st PUC Physics Previous Year Question Paper March 2018

**Bangalore North District**

**First PUC Annual Examination, March 2018**

Time : 3.15 Hours

Maximum Marks: 70

General Instructions:

1. All parts are compulsory.

2. Answers without relevant diagram / figure / circuit wherever necessary will not carry any marks.

3. Numerical problems should be solved with relevant formulae.

Part – A

I. Answer ALL the following questions ( 10 × 1 = 10 )

Question 1.

What are fundamental units?

Question 2.

Define centripetal acceleration.

Question 3.

When is work done by the force positive?

Question 4.

Express torque in vector form.

Question 5.

Give the relation between stress and strain.

Question 6.

State Pascal’s Law.

Question 7.

What is magnus effect?

Question 8.

Define heat capacity.

Question 9.

Mention the formulae for coefficient of performance of a refrigerator.

Question 10.

Define mean free path.

Part – B

II Answer any FIVE of the following questions. ( 5 × 2 = 10 )

Question 11.

Mention two fundamental forces in nature.

Question 12.

Write the dimensional formulae for a) Force b) Pressure

Question 13.

Define displacement and acceleration.

Question 14.

Give the representation for scalar product and Vector product of two vectors.

Question 15.

Mention any two methods of reducing friction. .

Question 16.

Write the general conditions for equilibrium of a rigid body.

Question 17.

Explain the application of surface tension idea in case of action of detergents.

Question 18.

What is simple harmonic motion? Give one example.

Part – C

III. Answer any FIVE of the following questions: ( 5 × 3 = 15 )

Question 19.

Derive an expression for maximum height of a projectile.

Question 20.

What is angle of banking? Mention an expression for maximum safe speed of a vehicle on a level road and express the symbols.

Question 21.

Distinguish between conservative and non conservative forces.

Question 22.

Compare the equations of linear motion with rotational motion.

Question 23.

State Kepler’s laws of planetary motion.

Question 24.

Derive an expression for Young’s modulas of a wire in terms of its radius.

Question 25.

Prove, that α_{v} = \(\frac{1}{T}\) for ideal gas.

Question 26.

Mention three assumptions of Kinetic theory of gasses.

Part – D

IV. Answer any TWO of the following questions. ( 2 × 5 = 10 )

Question 27.

What is Velocity-time graph? Derive the equation x = v_{0}t + \(\frac{1}{2}\) at^{2} by graphical method.

Question 28.

State and prove law of conservation of linear momentum.

Question 29.

Define Torque and angular momentum. Derive the relation between torque and angular momentum.

V. Answer any TWO of the following questions. ( 2 × 5 = 10 )

Question 30.

Explain different stages of Carnot’s cycle with P-V diagram.

Question 31.

Derive an expression for time period of oscillating bob of simple pendulum.

Question 32.

Mention the differences between progressive and stationary waves.

VI. Answer any THREE of the following questions: ( 3 × 5 = 15 )

Question 33.

An aircraft executes a horizontal loop of radius 1 Km with a steady speed of 900 Kmph. Compare its centripetal acceleration with acceleration due to gravity.

Question 34.

A man weighing 49 Kg carries a bag of 2 Kg. He climbs to the top of a building 100 m tall in 5 minute. Calculate the work done by the man and the power he develops.

Question 35.

Calculate ‘g’ at the bottom of a mine 8 Km deep and at an altitude 32 Km above the earth’s surface, radius of earth = 6.4 × 10^{6} m and g on earth’s surface = 9.8 m/s^{2}.

Question 36.

A cubical ice box of thermocol has each side 30 cm and thickness 5 cm. 4 Kg of ice is put in the box, if outside temperature is 45°C and coefficient of thermal conductivity is 0.01 JS^{-1} m^{-1} K^{-1}. Calculate the mass of ice left after 6 hrs. Take latent heat of fusion of ice is 335 × 10^{13} J Kg^{-1}.

Question 37.

The apparent frequency of a note when an observer moves towards a stationary source with a velocity 20 m/s is 200 Hz. Calculate the actual frequency of a note. Also, Calculate wavelength if Velocity of sound in air is 350 m/s.

**Dakshina Kannada District**

**First PUC Annual Examination, March 2018**

General Instructions:

1. All parts are compulsory.

2. Answers without relevant diagram / figure / circuit wherever necessary will not carry any marks.

3. Numerical problems should be solved with relevant formulae.

Part – A

I. Answer All questions: ( 10 × 1 = 10 )

Question 1.

Which component of Velocity of a projectile remains constant throughout the time of flight?

Question 2.

State work-energy theorem.

Question 3.

In which type of collision, the two bodies stick together after collision?

Question 4.

What is the total external force on a system of particles when its total momentum remains constant?

Question 5.

Write the relation between escape velocity and orbital velocity of a satellite revolving close to Earth surface.

Question 6.

What is a Venturimeter?

Question 7.

What is the Mode of heat transfer through a solid?

Question 8.

Mention the S.I. unit of Young’s Modulus.

Question 9.

Define specific heat capacity of the substance.

Question 10.

How does average kinetic energy of a gas molecule depend on the absolute temperature?

Part – B

II. Answer any Five of the following questions: ( 5 × 2 = 10 )

Question 11.

Mention the strongest and weakest force among the fundamental forces in nature.

Question 12.

Draw position time graph for a particle moving with:

i) negative velocity

ii) positive acceleration

Question 13.

What is a Projectile? Give an example.

Question 14.

Show that power is equal to the dot product of force and velocity.

Question 15.

Define Radius of Gyration. Write the expression for Moment of Inertia in terms of Radius of Gyration.

Question 16.

State Kepler second law and third law of Planetary motion.

Question 17.

Suggest two methods of reducing friction. ,

Question 18.

At where is kinetic energy of a particle executing SHM:

(i) Maximum and

(ii) Minimum

Part – C

III. Answer any Five of the following questions: ( 5 × 3 = 15 )

Question 19.

Using the principle of homogeneity of dimensions, check the dimensional consistency of the equation.

T^{2} = \(\frac{4 \pi^{2} r^{3}}{G M}\) where, T is time period , G is gravitational constant, M is mass and r is orbital radius.

Question 20.

Obtain an expression for time of flight of a Projectile.

Question 21.

What is Static Friction? State laws of Static Friction.

Question 22.

State and explain theorem of perpendicular axes applicable to a planar body.

Question 23.

Draw a typical stress-strain curve for a metal. Hence, locate:

(i) yield point

(ii) fracture point

Question 24.

Distinguish between streamline flow and turbulent flow.

Question 25.

Deduce α_{v} = \(\frac{1}{T}\) for an ideal gas with usual notation.

Question 26.

What is a degree of Freedom? Mention the number of degrees of freedom of a monoatomic and diatomic gas molecule.

Part – D

IV. Answer any Two of the following questions: ( 2 × 5 = 10 )

Question 27.

Using velocity time graph, derive v^{2} = v_{0}^{2}+ 2ax, where the symbols have their usual significance.

Question 28.

State Newton second law of Motion. Hence, derive \(\vec{F}=m \vec{a}\).

Question 29.

Define angular momentum of a particle. Prove that the time rate of change of angular momentum is equal to torque acting on the particle.

V. Answer any Two of the following questions: ( 2 × 5 = 10 )

Question 30.

What is Thermal Radiation? List four properties of Thermal Radiation.

Question 31.

Derive an expression for Time period and hence frequency of an oscillating Simple Pendulum.

Question 32.

What is an Open Pipe? Discuss the modes of vibration of the air column in an open pipe.

VI. Answer any Three of the following questions: ( 3 × 5 = 15 )

Question 33.

A football player kicks a ball at a distance 10 m from a vertical pole at an angle of 45°. The ball just clears the tip of the pole and falls at a distance of 10 m on the other side. Determine the height of the vertical pole.

Question 34.

A Car weighing 900 Kg moving with a velocity of 20 ms^{-1} is uniformly accelerated with an acceleration of 2ms^{-2} for 10 second. Calculate the work done and the force required to accelerate the Car.

Question 35.

An artificial satellite revolves round the Earth at a height 700 km from the surface. Calculate its:

(i) Kinetic energy

(ii) Potential energy

(iii) Total energy

Given : Mass of satellite = 150 Kg

Mass of the Earth = 6 × 10^{24} Kg

Radius of the Earth = 6,400 Km.

Question 36.

A heat engine absorbs 2 kJ of heat from a reservoir at 150°C and rejects 0.5 kJ of heat to a sink in one complete cycle. Calculate:

(i) Efficiency of the Engine.

(ii) Temperature of the sink.

(iii) Work done by the heat engine during each cycle.

(iv) Efficiency of the engine if the temperature of the sink is further decreased by 50K.

Question 37.

A train moving at a speed of 30 ms^{-1} approaches a station and sounds a horn of frequency 500 Hz. What is the apparent frequency of the horn as heard by a man on the platform as the train approaches him. Calculate the change in frequency as heard by the Man.

Given : Speed of Sound = 340 ms^{-1}

**Mysore District**

**First PUC Annual Examination, March 2018**

General Instructions:

1. All parts are compulsory.

2. Answers without relevant diagram / figure / circuit wherever necessary will not carry any marks.

3. Numerical problems should be solved with relevant formulae.

Part – A

I. Answer All questions: ( 10 × 1 = 10 )

Question 1.

Who discovered positron?

Question 2.

How many significant figures are there in 0.027 × 10^{3} m?

Question 3.

What does the slope of x -t graph represent?

Question 4.

Define unit vector.

Question 5.

Express 1k Whr injoules.

Question 6.

What is a rigid body?

Question 7.

Young’s modulus of steel is greater than that of copper. What does it mean?

Question 8.

At which temperature, density of water is maximum.

Question 9.

What is the significance of I-Law of thermo-dynamics?

Question 10.

How does average kinetic energy of a gas molecule depend on it’s temperature?

Part – B

II. Answer any Five of the following questions: ( 5 × 2 = 10 )

Question 11.

Check the correctness of the equation F = \(\frac{m v^{2}}{r}\) dimensionally, where the symbols have usual meaning.

Question 12.

Distinguish between path length and displacement.

Question 13.

What is centripetal acceleration? Write an expression for magnitude of centripetal acceleration.

Question 14.

Write any two methods of reducing friction.

Question 15.

State Pascal’s law of transmission of fluid pressure. Give any one of it’s applications.

Question 16.

Write any two differences between streamline flow and turbulent flow.

Question 17.

Define (a) free vibrations and (b) forced vibrations.

Question 18.

What is Doppler effect? Write the general expression for apparent frequency when both source and the observer are moving in the same direction.

Part – C

III. Answer any Five of the following questions: ( 5 × 3 = 15 )

Question 19.

Obtain the expressions for rectangular components of a given vector \(\vec{A}\) in x – y plane.

Question 20.

What is an impulsive force? Show that impulse of a force is equal to change in momentum.

Question 21.

State and prove work-energy theorem for a constant force.

Question 22.

State Kepler’s laws of planetary motion.

Question 23.

Draw stress versus strain curve for a metal and indicate the points of (a) Yield point, (b) Ultimate tensile strength and (c) Fracture point.

Question 24.

From Newton’s law of cooling, show that log_{e}(T_{2} – T_{1}) = -kt + C.

Question 25.

Using the law of equipartition of energy find the value of C_{p} & C_{v} for monoatomic gases and hence find their ratio.

Question 26.

Write Newton’s formula for velocity of sound in gases. Explain Laplace’s correction.

Part – D

IV. Answer any Two of the following questions: (2 × 5 = 10 )

Question 27.

What is v-t graph? Derive x = v_{0}t + \(\frac{1}{2}\) at^{2} by graphical method.

Question 28.

State Newton’s II- law of motion and hence derive \(\vec{F}=m \vec{a}\).

Question 29.

(a) Define radius of gyration.

(b) State and explain the theorems of perpendicular and parallel axes on moment of inertia.

V. Answer any Two of the following questions: ( 2 × 5 = 10 )

Question 30.

State and explain Newton’s law of gravitation. Establish the relation between g and G.

Question 31.

Describe the working of Carnot’s engine using P-V diagram.

Question 32.

Obtain the expression for time period of oscillation of a simple pendulum.

VI. Answer any Three of the following questions: ( 3 × 5 = 15 )

Question 33.

A hiker stands on the edge of a cliff 490 m above the ground and throws a stone horizontally with an initial speed of 15 ms^{-1}. Neglecting air resistance, find the time taken by the stone to reach the ground and the speed with which it hits the ground.

Question 34.

A body of mass 0.1 kg falling freely under gravity takes 10s to reach the ground. Calculate kinetic energy and potential energy of the body when the body has travelled for 6s.

Question 35.

The angular speed of a motor wheel is increased from 1200 rpm to 3120 rpm in 16 seconds,

(i) What is it’s angular acceleration?

(ii) How many revolutions does the engine make during this time?

Question 36.

Two rods of copper and brass having the same length and cross section are joined end to end. The free end of the copper rod is kept at 273 K and the free end of the brass rod is kept at 373 K. Calculate the temperature of the junction of the two rods at steady state. Assume that thermal conductivity of copper is 4 times that of brass.

Question 37.

A wave travelling along a string is described by Y = 0.005 sin (80x – 3t) in which the numerical constants are in S.I. units. Calculate (a) the amplitude (b) the wave length (c) the period and (d) the frequency of the wave.

**Belgaum District**

**First PUC Annual Examination, March 2018**

General Instructions:

2. Answers without relevant diagram / figure / circuit wherever necessary will not carry any marks.

3. Numerical problems should be solved with relevant formulae.

Part – A

I. Answer All questions: ( 10 × 1 = 10 )

Question 1.

What are derived units?

Question 2.

Define null vector.

Question 3.

Give an example for inertia of motion.

Question 4.

Mention the expression for the work done by a spring force.

Question 5.

Write the relation between linear velocity and angular velocity .

Question 6.

Why liquid and gas do not posses modulus of rigidity?

Question 7.

State Pascal’s law.

Question 8.

Define specific heat capacity.

Question 9.

Name the working substance used in Carnot cycle.

Question 10.

How many degrees of freedom for a mono atomic gas molecule?

Part – B

II. Answer any Five of the following questions: ( 5 × 2 = 10 )

Question 11.

Name the (i) strongest (ii) weakest fundamental force in nature.

Question 12.

Write the dimensional formula for (i) Force and (ii) Pressure.

Question 13.

Distinguish between distance and displacement.

Question 14.

State and explain the law of triangle of vectors.

Question 15.

What is impulsive force? Give one example.

Question 16.

Define angular momentum. Write the expression for it.

Question 17.

Mention any two methods of transmission of heat.

Question 18.

A particle takes 32 seconds to make 20 oscillations. Calculate time period and frequency.

Part – C

III. Answer any Five of the following questions: ( 5 × 3 = 15 )

Question 19.

Derive the expression for the centripetal acceleration.

Question 20.

What is Friction? What are (a) Static Friction, (b) Limiting Friction.

Question 21.

Prove work – energy theorem for a constant force.

Question 22.

State and explain the parallel axis theorem.

Question 23.

Derive relation between ‘g’ and ‘G’.

Question 24.

State and explain Hooke’s law. Define modulus of elasticity.

Question 25.

Derive an expression for liquid pressure at a point inside the liquid.

Question 26.

Mention any three assumptions of kinetic theory of gases.

Part – D

IV. Answer any Two of the following questions:

Question 27.

What is velocity time graph? Derive the equation of motion X = v_{0}t + \(\frac{1}{2}\) at^{2} from v-t graph.

Question 28.

State and prove the law of conservation of linear momentum.

Question 29.

What is a rigid body? Derive an expression for the kinetic energy of a rolling body.

V. Answer any Two of the following questions: ( 2 × 5 = 10 )

Question 30.

What is isothermal process? Obtain the expression for work done in isothermal process.

Question 31.

Define simple hormonic motion. Mention the characteristics of simple hormonic motion.

Question 32.

Show that only odd hormonics arc present in the vibrations of air column in a closed pipe.

VI. Answer any Three of the following questions: ( 3 × 5 = 15 )

Question 33.

A cricketer can throw a ball to a maximum horizontal distance of 100 m. How much high above the ground can the cricketer throw the same ball?

Question 34.

A man weighing 48 kg carries a bag of 2 kg. He climbs to the top of a building 100 m tall in 5 minutes. Calculate the work done by the man and his power.

Question 35.

An earth satellite in a circular orbit a height of 200 km above the earth’s surface has a period of 80 minutes. Calculate the mass of the earth from this data, Radius of the earth – 6400 km.

Question 36.

A brass boiler has a base of area 0.16 m^{2} and thickness 1 cm. It boils water at the rate of 6 kg. min^{-1} when placed on a gas stove. Estimate the temperature of the part of the flame in contact with the boiler.

Given that: thermal conductivity of brass = 10^{9} JS m^{-1}t^{-1} k^{-1} and heat of vapourisation of water = 2256 × 10^{3} J kg^{-1}.

Question 37.

A train standing at the outer signal of a railway station blows a whistle of frequency 400 Hz still air,

(i) What is the frequency of whistle for a platform observer when the train.

(a) approaches the platform with speed of 10 ms^{-1}.

(b) recedes from the platform with speed of 10 ms^{-1}.

(ii) What is the speed of sound in each case? The speed of sound in still air 340 ms^{-1}.

**Dharwad District**

**First PUC Annual Examination, March 2018**

General Instructions:

2. Answers without relevant diagram / figure / circuit wherever necessary will not carry any marks.

3. Numerical problems should be solved with relevant formulae.

Part – A

I. Answer All questions: ( 10 × 1 = 10 )

Question 1.

Define absolute error.

Question 2.

What is position vector?

Question 3.

The force ‘F’ acting on a body displaces it through a distance ‘S’ perpendicular to its direction.

What is the work done by the force?

Question 4.

Write the relation connecting angular velocity and linear velocity.

Question 5.

State Hooke’s law.

Question 6.

Mention SI unit of pressure.

Question 7.

When the flow of the fluid is said to be steady flow?

Question 8.

Name the instrument used to measure temperature of the substance.

Question 9.

State zeroth law of thermodynamics.

Question 10.

Define mean free path.

Part – B

III. Answer any Five of the following questions: ( 5 × 2 = 10 )

Question 11.

Name any two fundamental forces in nature.

Question 12.

Mention any two applications of dimensional analysis.

Question 13.

Write any two differences between distance and displacement of a particle.

Question 14.

What is vector quantity? Give an example for it.

Question 15.

How linear momentum of a body vary with its mass and velocity?

Question 16.

Write two conditions for equilibrium of a rigid body.

Question 17.

State Pascal’s law. Name any one device which works on Pascal’s law.

Question 18.

Mention Newton’s formula for speed of sound in gases and explain the terms used.

Part – C

III. Answer any Five of the following questions: ( 5 × 3 = 15 )

Question 19.

Define centripetal acceleration. Mention an expression for centripetal acceleration and explain the symbols used.

Question 20.

Write any three advantages of friction.

Question 21.

Show that instantaneous power is equal to scalar product of force and velocity.

Question 22.

Obtain the relation connecting angular momentum and torque for a particle.

Question 23.

Derive an expression for acceleration due to gravity in terms of mass and radius of the earth.

Question 24.

Write any three applications of elastic behaviour of materials.

Question 25.

Mention any three factors on which amount of heat added to increase the temperature of the substance depends.

Question 26.

What is an ideal gas? Write ideal gas equation. At what condition real gases behaves as ideal gas?

Part – D

IV. Answer any Two of the following questions: ( 2 × 5 = 10 )

Question 27.

What is velocity – time graph? Derive V^{2} = V_{0}^{2}+ 2ax with usual notations using velocity – time graph.

Question 28.

Derive an expression for maximum safe speed of a car moving on banked circular road.

Question 29.

What is meant by moment of inertia? State and explain (a) Theorem of perpendicular axes and (b) theorem of parallel axes.

V. Answer any Two of the following questions: ( 2 × 5 = 10 )

Question 30.

Explain the working of Carnot engine with necessary P-V diagram.

Question 31.

Obtain an expression for period of oscillations of a load attached to a spring.

Question 32.

Derive an expression for fundamental frequency of oscillation of a stretched string.

VI. Answer any Three of the following questions: ( 3 × 5 = 15 )

Question 33.

A cricket ball is thrown at a speed 25 ms^{-1} in the direction 30° above the horizontal. Calculate:

(a) The maximum height reached by the ball and

(b) The time taken by the ball to reach the initial height. (Given: Acceleration due to gravity g = 9.8 ms^{-2} )

Question 34.

A overhead tank of volume 50m^{3} is to be filled with water in 30 minutes. If the tank is at a height of 6m, what is the power of the pump to be used?

(Given: density of water = 1000 Kg m^{-3}, Acceleration due to gravity g = 9.8 ms^{-2})

Question 35.

Calculate the orbital velocity and period of revolution of an artificial satellite of earth revolving at a height of 200 km from earth’s surface. (Given: Radius of the earth = 6400 km, Mass of the earth = 6 × 10^{24} Kg and Gravitational constant G = 6.7 × 10^{11} Nm^{2} kg^{-2})

Question 36.

A cylindrical copper rod of diameter 0.04 m and length of 0.5 m is heated at one end by steam. The other end is kept at 0°C. Find the quantity of heat conducted across any section per minute. (Given: thermal conductivity of copper s 385 W m^{-1} K^{-1}).

Question 37.

A train moving at a speed of 20 ms^{-1} towards a station sounding a whistle of frequency 500 Hz. Calculate the apparent frequencies of the whistle as heard by the man standing on the platform when the train

(a) Approaches him

(b) Recedes from him

(Velocity of sound in air is 330 ms^{-1})

**Bangalore South District**

**First PUC Annual Examination, March 2018**

General Instructions:

2. Answers without relevant diagram / figure / circuit wherever necessary will not carry any marks.

3. Numerical problems should be solved with relevant formulae.

Part – A

I. Answer All questions: ( 10 × 1 = 10 )

Question 1.

What is the basis of cesium atomic clock?

Question 2.

Which component of velocity is constant in a Projectile motion?

Question 3.

Define inertia.

Question 4.

State work – Energy theorem.

Question 5.

Mention the relation between Torque and angular momentum of a particle.

Question 6.

What are Elastomers?

Question 7.

State Bernoulli’s principle.

Question 8.

How does viscosity of a liquid changes with rise in temperature?

Question 9.

Mention the significance of zeroth law of thermodynamics.

Question 10.

How does an average Kinetic Energy of gas Molecules depend on the absolute temperature?

Part – B

II. Answer any Five of the following questions: ( 5 × 2 = 10 )

Question 11.

Write any two fundamental forces in nature.

Question 12.

Mention any two sources of systematic errors. .

Question 13.

Distinguish between path length and displacement.

Question 14.

Define the terms (i) Null vector or Zero vector (ii) Unit vector

Question 15.

Classify the nature of flow of liquid on the basis of Reynolds number.

Question 16.

Give Kelvin-plank statement and claussius statement.

Question 17.

What are free oscillations and forced oscillations?

Question 18.

What are longitudinal waves and transverse waves?

Part – C

III. Answer any Five of the following questions: ( 5 × 3 = 15 )

Question 19.

Obtain an Expression for time of flight of a projectile.

Question 20.

What is Friction? Write any two advantages of friction.

Question 21.

What is collision? Distinguish between Elastic collision and Inelastic collision.

Question 22.

State Kepler’s law of planetary motion.

Question 23.

Draw a typical Stress-Strain curve for a metal. Mention yield point and Fracture point.

Question 24.

Show that volume coefficient of thermal expansion α_{v} = \(\frac{1}{T}\) for ideal gas at constant pressure.

Question 25.

Mention any three assumptions of kinetic theory of gases.

Question 26.

Discuss modes of vibration of air column in a closed pipe.

Part – D

IV. Answer any Two of the following questions: ( 2 × 5 = 10 )

Question 27.

What is Uniform Circular Motion? Obtain an expression for centripetal acceleration.

Question 28.

Obtain an expression for maximum safe speed of a vehicle on a banked road in circular motion.

Question 29.

State and explain parallel axes theorem and perpendicular axes theorem.

V. Answer any Two of the following questions: ( 2 × 5 = 10 )

Question 30.

Obtain an expression for total energy of a satellite revolving in circular orbit around a planet.

Question 31.

Explain different stages of Carnot’s cycle with P-V- diagram.

Question 32.

Derive an expression for time period of oscillating bob of simple pendulum.

VI. Answer any Three of the following questions: ( 3 × 5 = 15 )

Question 33.

From a balloon ascending with a velocity of 9.8 ms^{-1}, a stone was dropped and it reached the ground in 1 Is. How high was the balloon? When the stone was dropped and with what velocity did it hit the ground. (g = 9.8 ms^{-2})

Question 34.

A pump on the ground floor of a building can pump up water to fill a tank of volume 30m^{3} in 15 minutes. If the

tank is 40m above the ground and efficiency of the pump is 30%. How much power is consumed by the pump? (Density of water 103 kgm^{-3}, g = 9.8 ms^{-2}).

Question 35.

A dental drill accelerates from rest to 900 rpm in 2 sec. What is the angular acceleration? How many revolutions does it make in coming to full speed?

Question 36.

Find the time for which a layer of ice 5 cm thick on the surface of a pond will increase its thickness by 0.1 cm when temperature of the surrounding air is – 20°C.

Thermal conductivity of ice = 2.1 Wm^{-1} K^{-1} density of ice = 900 Kg m-3

Latent heat of ice = 3.36 × 10^{5} J Kg^{-1}

Question 37.

Two cars are approaching each other on a straight road and moving with a velocity 60 Kmph. If the sound produced in one car is of frequency 500 Hz. What will be the frequency of sound as heard by a person sitting in another car? When the car has crossed and moving away from each other, what will be the frequency of sound as heard by the same person, (speed of sound in air is 332 ms^{-1}).