SHRI VIDHYABHARATHI MATRIC HR.SEC.SCHOOL

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1 SHRI VIDHYABHARATHI MATRIC HR.SEC.SCHOOL SAKKARAMPALAYAM, AGARAM (PO) ELACHIPALAYAM TIRUCHENGODE(TK), NAMAKKAL (DT) PIN-6370 Cell : , COMMON HALF YEARLY EXAMINATION DECEMBER - 08 STD: XI SUBJECT: PHYSICS ANSWER KEY MARKS : 70 Q. NO SECTION - I MARKS d) 7 % a) Torque and work done 3 a) increases 4 b) g = 5 ms - 5 a) 0 kg 6 c) greater than 7 c) static friction is not zero and kinetic friction is zero 8 c) 5gR 9 c) 0 < e < 0 b) 5 rad s - c) decreases in the month of July and increases in the month of January d) c) U > 0, Q > 0 4 c) 6.8 % 5 b) 0 A SHRI VIDHYABHARATHI MAT.HR.SEC.SCHOOL, SAKKARAMPALAYAM Page Kindly Download This Answer Key From Original Education Website - Avoid Duplicate Websites

2 Q. NO SECTION - II MARKS 6 Any four points (each point carries mark) 7 Scalars only magnitude. eg. distance, mass, temperature. 8 Vectors both magnitude and direction, eg. Force, velocity, displacement Types of friction Static, Kinetic and rolling friction. Methods to reduce friction Lubricating, using ball bearings, polishing the surface 9 Elastic collision * Total mometnum is conserved * Total kinetic energy is conserved * Forces involved are conservative forces * Mechanical energy is not dissipated Inelastic collision * Total momentum is conserved * Total kinetic energy is not conserved * forces involved are non conservative forces * Mechanical energy is dissipated into heat, light and sound etc., 0 W = F.s W = 30 x 0 = 300 J (without unit reduce mark) Stable and Unstable equilibrium any two differences (each difference carries mark) The negative sign in the total energy implies that the satellite is bound to the earth and it cannot escape from the earth 3 For small deformation stress is directly proportional to strain 4 σ ε γ Given PT γ = constant.. () Also P T 3 PT -3 = constant.. () Equating () and () PT γ = PT -3 T -3 = T - 3 = γ γ γ γ = 3/ SHRI VIDHYABHARATHI MAT.HR.SEC.SCHOOL, SAKKARAMPALAYAM Page γ γ Kindly Download This Answer Key From Original Education Website - Avoid Duplicate Websites

3 Q. NO SECTION - III MARKS 5 Relevant explanation or diagram sin θ = arc radius = D s D = s.θ (or) Linear diameter = distance x angular diameter 6 Vector product definition & equation Properties any 4 (each property carries mark) 7 Inertia Definition Types and explanation with examples 8 Conservative forces: * Work done is independent of path * work done in a round trip is zero * total energy remains constant * work done is completely recoverable * Force is the negative gradient of potential energy Non conservative forces: * work done depends upon the path * work done in a round trip is not zero * energy is dissipated as heat energy * work done is not completely recoverable * there is no relation between force and potential energy 9 We know that r = m r + m r 30 r = 0 m +m 3i + j + 4k + 5 (3i + 6j + 5k 0+5 r = 3i j k m Kepler s laws: * Each planet moves around the sun in an elliptical orbit with the sun at one of the foci. * The radial vector (line joining the sun to a planet) sweeps equal areas in equal intervals of time. * The square of the time period of revolution of a planet around the sun in its elliptical orbit is directly proportional to the cube of the semi-major axis of the ellipse. SHRI VIDHYABHARATHI MAT.HR.SEC.SCHOOL, SAKKARAMPALAYAM Page 3 Kindly Download This Answer Key From Original Education Website - Avoid Duplicate Websites

4 3 Streamlined flow * When a liquid flows such that each particle of the liquid passing through a point moves along the same path with the same velocity as its predecessor then the flow of liquid is said to be a streamlined flow. It is steady or laminar flow. * The velocity of the particle at any point is constant * The actual path taken by the particle of the moving fluid is called a streamline, which is a curve, the tangent to which at any point gives the direction of the flow of liquid. Turbulent flow * When the speed of the moving fluid exceeds the critical speed V c, the motion becomes turbulent. * The velocity changes both in magnitude and direction from particle to particle. * The path taken by the particles is turbulent flow becomes erratic and whirlpool like circles called eddy current or eddies. 3 * When the given gas is kept at constant temperature, the pressure of the gas is inversely proportional to the volume. P V * at constant pressure, volume of the gas is directly proportional to the absolute temperature. V T Combining these two equations PV = CT PV = NkT ( C = Nk) N = μ NA PV = μ NA kt PV = μ RT ( NA k = R) 33 u = 40 km/hr, v = 0, s = m 40 x 03 u = = ms- v = u + as (v = 0) u = - as u = - x a x a = - 3 ms - SHRI VIDHYABHARATHI MAT.HR.SEC.SCHOOL, SAKKARAMPALAYAM Page 4 Kindly Download This Answer Key From Original Education Website - Avoid Duplicate Websites

5 u = - as s = u / 6 s = s = 7.96 m Q. NO SECTION - IV MARKS The principle of homogeneity of dimensions states that the dimensions of all the terms in a physical expression should be the same Uses: (i) (ii) (iii) to convert a quantity from one system to another to check the dimensional correctness of a given equation to establish a relation between different quantities eg: Examples for each uses st law : Every object continues to be in the state of rest or of uniform motion (constant velocity) unless there is external force acting on it. nd law: Force acting on an object is equal to rate of change of its momentum rd law: For every action there is an equal and opposite reaciton Significance Any five properties of scalar product (each point carries mark) Any five properties of vector product (each point carries mark) Diagram Explanation Maximum height: The maximum vertical distance travelled by the projectile during its journey SHRI VIDHYABHARATHI MAT.HR.SEC.SCHOOL, SAKKARAMPALAYAM Page 5 Kindly Download This Answer Key From Original Education Website - Avoid Duplicate Websites

Range: The amximum horizontal distance between the point of projection and the point on the horizontal plane where the projectile hits the ground when θ = π/4, Diagram Explanation upto upto 36 The

6 Range: The amximum horizontal distance between the point of projection and the point on the horizontal plane where the projectile hits the ground when θ = π/4, Diagram Explanation upto upto 36 The total energy at the point = total energy at point minimum speed at the highest point SHRI VIDHYABHARATHI MAT.HR.SEC.SCHOOL, SAKKARAMPALAYAM Page 6 Kindly Download This Answer Key From Original Education Website - Avoid Duplicate Websites

7 36 Moment of inertia of a body about any axis is equal to the sum of its moment of inertia about a parallel axis through its center of mass and the product of the mass of the body and the square of the perpendicualr distance between the two axis. I = I c + Md Diagram 37 Escape speed: Explanation Upto Upto E f = 0 replace v i with v e Upto SHRI VIDHYABHARATHI MAT.HR.SEC.SCHOOL, SAKKARAMPALAYAM Page 7 Kindly Download This Answer Key From Original Education Website - Avoid Duplicate Websites

8 37 Statement: The sum of pressure energy kinetic energy and potential energy per unit mass of incompressible non viscous fluid in a streamlined flow remains constant. Diagram Upto Conduction definition and explanation Convection definition and explanation Radiation definition and explanation Explanation SHRI VIDHYABHARATHI MAT.HR.SEC.SCHOOL, SAKKARAMPALAYAM Page 8 Kindly Download This Answer Key From Original Education Website - Avoid Duplicate Websites

9 ********* Department of Physics SHRI VIDHYABHARATHI MATRIC HR.SEC.SCHOOL SAKKARAMPALAYAM, AGARAM (PO) ELACHIPALAYAM TIRUCHENGODE(TK), NAMAKKAL (DT) PIN-6370 Cell : , , SHRI VIDHYABHARATHI MAT.HR.SEC.SCHOOL, SAKKARAMPALAYAM Page 9 Kindly Download This Answer Key From Original Education Website - Avoid Duplicate Websites

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