UNIT – V



CLASS XI PHYSICS – QUESTION BANK

|1 |Derive an expression for the maximum velocity required for a car on a banked road by taking into account the force of friction for safe turn. |

|2 |State parallelogram law of vector addition. Derive equation for the magnitude and direction of the resultant vector. |

|3 |a) Define an expression for the orbital velocity of a satellite and escape velocity of a satellite. |

| |b) The orbiting velocity of an earth-satellite is 8 Km/s. Find out the value of escape velocity. |

|4 |a) Define an expression for acceleration due to gravity below the surface of earth. |

| |b) At what depth, below the surface of the earth, the value of g becomes 25% of its value on the surface of earth? ( Radius of earth= 6400 Km). |

|5 |1) What are stationary waves? |

| |2)A wave traveling along a string is described by, Y (x,t) = 0.005 sin (80.0x-3.0t), in which the numerical constants are in SI units ( 0.005m,80.0rads-1 |

| |and 3.0 rads-1). Calculate a) the amplitude b) the wavelength and c) the period and frequency of the wave. Also calculate the displacement of the wave at a |

| |distance x=30.0cm and time t = 20s. |

|6 |Show that the path of a projectile, if projected at an angle “θ” with the horizontal, is a parabola.Obtain expression for maximum height, Time of flight |

| |and Range of a projectile. |

| |Show that the path of a projectile, if projected at an angle “θ” with the horizontal, is a parabola. A cricket ball is thrown at speed of 28 m/s in a |

| |direction 30° above the horizontal. |

|7 |Derive all the three equation of uniformly accelerated linear motion graphically. |

|8 |Define: Uniform circular motion and centripetal acceleration. Derive an expression for magnitude of centripetal acceleration and centripetal force and show |

| |the direction of it with the help of neat diagrams |

|9 |Derive an expression for the excess of pressure inside a drop of liquid. |

|10 | Represent the variation of stress –strain in a ductile material and explain the nature of variation on each other mentioning about elastic region, |

| |plastic region, permanent set, tensile strength, yield point and breaking point . Also explain an application of elasticity. |

|11 |State and prove Bernoulli’s theorem. Give an example of its application. |

|12 |Using Pascal’s law, explain with a neat figure, the working of a hydraulic lift. Mention any one situation from your daily life where hydrostatic paradox |

| |is useful. |

|13 |What is terminal velocity ? Derive an expression for it. |

|14 |Derive an expression for the total energy of a particle undergoing simple harmonic motion. |

| |For a particle executing simple harmonic motion, find the distance from the mean position at which its potential and kinetic energies are equal. |

|15 |Draw the stationary wave pattern in the fundamental mode for the following cases: (i) an open organ pipe (ii) resonance column apparatus (iii) a rigid |

| |metallic rod clamped in the middle, the rod is hit with a stick at one of its free ends. |

| |(b) If an open organ pipe of length 20cm resonates with 1 kHz, in the third harmonic mode, find the wave length of the standing wave produced. |

|16 | (a) Show that small oscillations of a pendulum execute SHM and hence Obtain expression for time period of a simple pendulum. |

| |b) What do you mean by free, damped and forced oscillations? |

|17 |Derive Newton and Laplace for velocity of sound. |

|18 |Draw i) position – time ii) velocity – time and iii) acceleration – time for the motion of an object under free fall |

| |A car is moving along a straight line in the given figure. It moves from O to P in 18 seconds and returns from P to Q in 6 seconds. What are the average |

| |velocity and average speed of the car in going (a) from O to P? and (b) from O to P and back to Q? |

| |[pic] |

|19 |A monkey is sitting on a tree. Rahim seeing the Monkey brought some fruits and gave them to the Monkey, and ran into the house immediately. On hearing the |

| |sound produced when Rahim was running the monkey was scared and climbed the nearby tree. (a) What values of Rahim inspired you? (b)A monkey of mass 40 Kg |

| |climbs on a rope which can stand a maximum tension of 600 N . In which of the following cases will the rope will break. The monkey (I) Climbs up with an |

| |acceleration of 6 m/s2 (II) Climbs down with an acceleration of 4 m/s2 (III) Climbs up with a uniform speed of 5 m/s (IV) Falls down the rope nearly under |

| |gravity? (Take g= 10 m/s2) (Ignore the mass of the rope |

| |ANS : |

| |Ans: (a1) Rahim loves animals and feeds them, don’t frighten animals with (b) (I) The tension developed in the string when the monkey climbs up with an |

| |acceleration of 6 m/s2 is given by T = m(g + a) = 40 (10 + 6) =640 N (II) The tension developed when the monkey climbs down with an acceleration of 4m/s2 Is|

| |given by T = m (g-a) = 40(10-4) = 40 x 6 = 240 N (III)When the monkey climbs with a uniform speed of 5m/s acceleration is zero and the tension in the string|

| |is T = mg 40 x 10 = 400 N (IV)As the monkey falls down the rope nearly under gravity, the tension in the string is given by, T = m(g-a) = m(g-g) 0 Since the|

| |string can withstand a maximum tension of 600 N, hence the rope will break only in the first case (I). |

|20 |Suresh noticed a big Granite Rock in his locality. He thought that if they worked upon it they could earn money. He took permission from the Government, |

| |completed all the formalities .He broke the Rock using a bomb. The rock was made into slices .They established a Granite industry. Many of the people in the|

| |surroundings started to earn and live comfortably. (a) What values of Suresh impress you? (b)A bomb is thrown in a horizontal direction with a velocity of |

| |50 m/s. It explodes into two parts of masses 6 Kg and 3 Kg. the heavier fragment continues to move in the horizontal direction with a velocity of 80 m/s |

| |.Calculate the velocity of the lighter fragment. Ans: (a) Suresh knows how to utilize the natural resources, has got concern for others. Also he knows how |

| |to complete all legal formalities before taking up any work. (b) According to law of conservation of momentum Total momentum of fragments = Momentum of the |

| |Bob m1v1 +m2v2 = MV 6X80 + 3X v2 =9 X 50; v2 = -10 m/s |

|21 |State and prove: “Law of conservation of linear momentum” for two colliding objects. |

| |A batsman hits back a ball straight in the direction of the bowler without changing its initial speed of 12 m/s. If the mass of the ball is 0.15 kg, |

| |calculate the impulse imparted by the ball (assume linear motion of the ball |

|22 | What do you mean by beat frequency? |

| |2) a) Two sitar strings A and B playing the note 'Dha' are slightly out of tune and produces beats of frequency 5 Hz. The tension in the string B is |

| |slightly increased and the beat frequency is found to decrease to 3 Hz. What is the original frequency of B if the frequency of A is 427 Hz? |

| |b) A rocket is moving at a speed of 200 m/s towards a stationary target. While moving it emits a wave of frequency 1000 Hz. Some of the sound reaching the |

| |target gets reflected back to the rocket as an echo. Calculate 1) The frequency of the sound as detected by the target and 2) The frequency of the echo as|

| |detected by the rocket.( Velocity of sound= 330m/s). |

|23 |a) Define an expression for acceleration due to gravity below the surface of earth. |

| |b) At what depth, below the surface of the earth, the value of g becomes 25% of its value on the surface of earth? ( Radius of earth= 6400 Km) |

|24 |State: Newton’s law of cooling. |

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| |(b)Using it find the time taken by a hot food in a pan to cool from 71oC to 69oC, If the room temperature is 20oC. The food cools from 94oC to 86oC in 2 |

| |minutes |

| | VALUE BASED POINTS |

| |Helping / Brave / Kind / Knowledge about AC or DC / Knowledge about insulator & conductors/ Awareness about safety precautions/concern for the |

| |student/inquisitiveness for practical knowledge/Presence of mind, careful, helpful/Awareness etc./Helpful & Considerate/Gratefulness/Responsive / caring and|

| |concerned / encouraging /Scientific temperament / curiosity / learning attitude / any other quality/ concern for conservation of resources/convincing , |

| |thoughtful etc/Co-operative attitude and scientific temperament/Concern for students / Helpfulness / Professional honesty/Scientific temperament/– Social |

| |Awareness, understanding nature, concern for society /Knowledgeable, professional honesty, concern for society/helpful, concern for others , caring |

| |nature/generous, helping nature, caring/Following the rules/regulations/ Responsible citizen/Curiosity, power of observation/ |

PHYSICS - TWO AND THREE MARK QUESTIONS

|1 |The percentage of errors in the measurement of mass and velocity are 2 and 3 respectively. Calculate percentage of error in the measurement of K.E. |

|2 |Name the physical quantities which are calculated from |

| |Slope of the given Graph |

| |Area under the given Graph |

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|3 |State Newton’s II & III law of motion. |

|4 |State the laws of friction. |

|5 |Derive an expression for K.E of rotation. |

|6 |Derive a relationship between ‘g’ and ‘G’. |

|7 |Estimate is the pressure on a swimmer 10 m below the surface of a lake. |

|8 |Distinguish between isothermal and adiabatic process. |

|9 |What is a heat engine? Write the formula for it's efficiency. |

|10 |Define simple Harmonic Motion? |

|11 |Differentiate between longitudinal and transverse wave. |

|12 |Find the angle between[pic]and [pic] |

|13 |State and prove the law of conservation of a momentum. |

|14 |A constant force acting on a body of mass 3Kg changes its speed from 2 to 3.5ms-1 in 25 seconds. What is the magnitude of the applied force? |

|15 |Derive an expression for the potential energy of a spring. |

|16 |What is centre of mass? Derive an expression for the centre of mass of a two particle system. |

|17 |At what height above the earth’s surface, the value of g is same as in a mines 80 Km deep? |

|18 |A body of mass 5 Kg initially at rest is subject to a force of 20 N. What is the Kinetic energy acquired by the body at the end of 10 seconds? |

|19 |State and prove work – energy theorem. |

|20 |Obtain an expression for the maximum constant velocity acquired by a body while freely falling in a viscous medium. |

|21 |A flask contains Argon and chlorine. The temperature of the mixture is 270C. Obtain the ratio of a) Average KE per molecule b) rms speeds of the |

| |molecule. |

|22 |Two waves of nearly same frequencies traveling in the same direction superimpose on each other. Name the resulting phenomenon. |

|23 |Define relative error and percentage error in a measurement. |

|24 |Show that for a given angle of projection and initial velocity, the ratio between maximum height attained by a projectile and range of projectile is|

| |¼ tanθ |

|25 |Define: (a) stopping distance of a vehicle; (b) reaction time during a free fall. |

|26 |Define: centre of mass. Give an example where in the centre of mass lies outside the object. |

|27 |State: “law of areas” in planetary motion and hence show that the speed of a planet in perihelion position is greater than that in the aphelion |

| |position. |

|28 |Explain how anomalous behaviour of water helps in protecting animal and plant life. |

|29 |(a) State: Stoke’s law in viscosity. |

| |(b) What is the force acting on a solid moving with terminal velocity through a liquid of coefficient of viscosity ‘ƞ’? |

|30 |(a) Define the term: angle of contact. |

| |(b) Why is it difficult to blow an air bubble of very small radius? |

|31 |Define ‘mean free path’ of gas molecules. State any two postulates of kinetic theory of gases. |

|32 |What are elastomers? Give two examples for the same. |

|33 |Define ‘isochoric’ process. What is the work done in such process? |

|34 |State Newton’s laws of motion. |

|35 |State and prove law of conservation of mechanical energy in a free fall with a necessary diagram. |

|36 |(a) What are conservative forces? Give an example. |

| |(b) Distinguish between elastic and in elastic collisions. |

| |(c) If the force applied on an object is 5N and the power expended by it 20W, what is the velocity of the object? |

|37 |(a) Write the equation with the expansion of symbols for ‘parallel axes theorem’ of moment of inertia. |

| |(b) Using it find the moment of inertia of a ring of mass ‘m’ and radius ‘r’ about an axis passing through the tangent to the circle of the ring. |

|38 |Derive an expression for orbital velocity and hence write the expression for the time period of a satellite. |

|39 | |

| |Using Pascal’s law, explain with a neat figure, the working of a hydraulic lift. Mention any one situation from your daily life where hydrostatic |

| |paradox is useful. |

|40 |(a)State: Newton’s law of cooling. |

| |(b)Using it find the time taken by a hot food in a pan to cool from 71oC to 69oC, If the room temperature is 20oC. The food cools from 94oC to 86oC in|

| |2 minutes. |

|41 |(a)Give any one difference between a refrigerator and a heat engine. |

| |(b)Write the expression for co-efficient of performance of a refrigerator in terms of heat released and heat absorbed. |

| |(c)What type of thermodynamic process is associated with sudden bursting of an inflated balloon? |

|42 |What do you mean by resonance? |

| |Mention any two uses of it from your daily life. |

|43 |Draw the fundamental modes of vibration of stationary waves in a) a closed pipe b) an open pipe |

|44 |Differentiate heat engine and heat pump with the help of block diagrams. |

|45 |Derive an expression for the excess of pressure inside a drop of liquid? |

|46 |a) Define degrees of freedom. b) How many degrees of freedom do a |

| |mono atomic gas and a diatomic gas have? |

|47 |It is advised not to stand near a running train. Explain. |

|48 |What is the apparent weight felt by a person in an elevator, when it is accelerating a) upward by 'a' b) downward by 'a'. |

|49 |If the earth shrinks suddenly, what will happen to the length of the day? Give reason. |

|50 |a) Give the location of centre of mass of 1. Solid Sphere 2. Solid Cylinder. |

| |b) Does the centre mass of a body necessarily lie on the surface of the body? Give an example |

|51 |Prove that the torque is rate of change of angular momentum. |

|52 |Give one example each for a) positive work and b) negative work. |

|53 |a) Define gravitational potential energy of a body? |

| |b) Write the formula for gravitational potential energy of an object. |

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|54 |Represent displacement, velocity and acceleration of a particle executing simple harmonic motion graphically. |

|55 |If the velocities of four particles in m/s are v1,v2,v3and v4 respectively, Write down the formula to find 1) Average speed and 2) r.m.s speed of the |

| |system of four particles. |

|56 |Name the physical quantity which is having dimension 1) ML2T-3; 2) MT-2; and 3) M-1L3T-2. |

|57 |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 m/s. Neglecting air |

| |resistance, find the time taken by the stone to reach the ground and the speed with which it hits the ground.( Take g = 9.8 m/s2) |

|58 |A cricket ball is thrown at a speed of 28 m/s in a direction 300 above the horizontal. Calculate a) the maximum height b) the time taken by the ball |

| |to return to the same level and c) the distance from the thrower to the point where the ball returns to the same level. |

|59 |Unit vectors i and j are along x and y axis respectively. Find out the magnitude and direction of vectors i+j and i-j ? |

|60 |In a ballistic demonstration a police officer fires a bullet of mass 50.0 g with speed 200 m/s. on soft ply wood of thickness 2.00 cm. The bullet |

| |emerges with only 10% of its initial kinetic energy. What is the emergent speed of the bullet ? |

|61 |Name three modes of transfer of heat. Give one application in each case |

|62 |What do the following velocity-time graphs represent? Write down the nature of motion of the body in each case. |

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|63 |A metal block of area 0.10 m2 is connected to a 0.010 Kg mass via a string that passes over an ideal pulley ( considered mass less and frictionless) |

| |as shown in the diagram. A liquid with a film thickness of 0.30 mm is placed between the block and the table. Find the coefficient of viscosity of the|

| |liquid when the block moves to the right with a constant speed of 0.085 m/s. |

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V m/s

T s

0

V m/s

V m/s

0

Time (s)

Time (s)

0

0

0

Time (s)

(1)

(2)

(3)

String

Pulley

.

Film

0.01Kg

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