S Grade X Physics CW Sheets Name RADIOACTIVITY 1. What is the name given to atoms of a substance which have the same atomic number but different mass numbers? 2. What is the difference in the atomic structures of such atoms? What are radio isotopes? Mention any two uses of them 3. What is back ground radiation. Mention the sources of back ground radiation. 4. What will an alpha particle change into when it absorbs:- a. One electron b. Two electrons? 5. Mention at least four precautions to be taken while handling radio active elements. 6. How many alpha and beta particles are emitted when Uranium nucleus 238 92U decays to Lead 206 82Pb? 7. Explain why alpha and beta particles are deflected in the electric field and magnetic field but gamma rays are not deflected in such field. Show the deflection of the radio active rays with a neat diagram 8. Define radioactivity? When does the nucleus of an atom become radioactive? How is the radioactivity of an element affected when it undergoes a chemical change to form a chemical compound? 9. A A nucleus Z X emits an α particle followed by γ emission, thereafter it emits two β particles to form X 3. a. Copy and complete the values of A and Z for X 3 A ZX X γ 1 X 2β 2 X 3 b. Out of alpha, beta and gamma radiations i. Which radiation is the most penetrating? ii. Which radiations are negatively charged SOUND 1. Give one example each of natural vibration, forced vibration & resonance. Mention one practical use of echo. 2. State three characteristics of musical sound. How does the musical sound differ from noise? 3. How does a stretched string on being set into vibration, produce an audible sound? Will this sound be audible if the string is set into vibration on the surface of moon? Give reason for your answer 4. Radio waves of speed 3x10 8 m/s are reflected off the moon and received back on earth. The time elapsed between the sending and receiving it back at the earth station is 2.5sec.What is the distance of moon from the earth? 5. An observer stands at a distance of 850m from a cliff and fires a gun. After what time gap will he hear the echo, if speed of sound in air is 350m/s? 6. a. Give one example each of natural vibration and forced vibration b. Differentiate between natural vibration & forced vibration. 7. What is meant by an echo? Mention the important conditions that are necessary for an echo to be heard distinctly? Mention one practical use of echo. 8. State three characteristics of musical sound? Mention one factor on which each of them depend? 9. How does the musical sound differ from noise? 10. A vibrating tuning fork is placed over the mouth of a burette filled with water. The tap is opened and the water level gradually falls. It is observed that the sound becomes the loudest for a particular length of air column. a. What is the name of the phenomenon taking place when this happens? b. Why the sound becomes the loudest? c. What is the name of the phenomenon taking place for another length of air column where is not the loudest? 11. Why soldiers are asked to break their rhythmic steps while crossing a bridge. 12. A person is tuning his radio set to a particular station. What is the person trying to do? Name and define the phenomenon involved in tuning the radio set. 13. What is the principle on which sonar is based?
LIGHT 1. Draw a ray diagram to illustrate how a ray of light incident obliquely on one face of a rectangular glass slab of uniform thickness emerges parallel to its original direction. Mention which pairs of angles are equal. 2. What is meant by the statement, the critical angle for diamond is 24º? How is the critical angle of the material related to its refractive index? 3. Express the refractive index μ of a medium a. In terms of the velocity of light; b. In terms of the angle of incidence i in air and the angle of refraction r in a denser medium. 4. Mention two properties of a wave: one property which varies and the other which remains constant when the wave passes from one medium to another. 5. Mention any two differences between reflection of light from a plane mirror and total internal reflection of light from a prism 6. Name any two electromagnetic waves which have a frequency higher than that of violet light. State one use of each. 7. Why are infrared radiations preferred over ordinary visible light for taking photograph in fog? 8. A particular type of high energy invisible electromagnetic rays help us to study the structure of crystals. Name these rays and give another important use of these rays. 9. a. In the diagram given below, a ray of light PQ is incident normally on one face AB of an equilateral glass prism. What are the angles of incidence at the faces AB and AC? b. Complete the ray diagram showing its emergence into air after passing through the prism. 10. a. What do you understand by the term refraction of light? b. How does the light ray deviate when it travels from a rarer medium to a denser medium 11. a. what do you mean by total internal reflection? b. what are the necessary conditions to obtain total internal reflection? 12. a. Define dispersion of light. b. Explain briefly how white light gets dispersed by a prism 13. a. During sunrise and sunset the sky appears red, why? b. Draw a ray to show the action of convex lens as magnifying glass? FORCE 1. What do you understand by the term momentum? 2. State two factors which determine momentum of a body. 3. Is momentum a scalar or a vector quantity? 4. State unit of momentum in the SI system 5. Define the term force. 6. State the effects of a force applied on, a. Non-rigid body, b. Rigid body. 7. State the effects a force can produce. Give one example of each effect. 8. Define Newton s second law of motion 9. How is the force related to the momentum of a body? 10. What do you understand by, a. Mass, b. Weight. 11. How is the weight of body related to its mass? 12. Distinguish between mass and weight. 13. A body having a velocity of 200 ms 1 has a momentum of 5 Ns. Find the mass of the body. 14. Calculate the momentum of an electron of mass 9 10 31 kg, moving with a velocity of 6 10 7 ms 1. 15. Two balls of mass ratio 1 : 2 are dropped from the same height. Find : a. The ratio between their velocities, when they strike the ground. b. The ratio of forces acting on them during the motion. 16. Calculate the mass of a body, when a force of 525 N, produces an acceleration of 3.5 ms 2. 17. A golfer hits a golf ball at rest, such that the contact between the ball and golf stick is for 0.1 s. If the golf ball covers a linear distance of 400 m in 2 s, calculate the magnitude of force applied. Mass of golf ball is 50 g.
WORK, POWER AND ENERGY 1. Define work. 2. State the conditions for doing work. 3. State the mathematical expression for work when displacement is produced in its own direction. 4. State the mathematical expression for work when the force acts at an angle to the direction of displacement of body. 5. How is work done measured? 6. State and define unit of work in CGS system. 7. State and define unit of work in SI system. 8. Derive a relation between joule and erg. 9. What should be the angle between the force and the displacement to get a. Minimum work, b. Maximum work. 10. A body is acted upon by a force, state two conditions when work done is zero. 11. State the condition when the work done by a force is a. Positive, b. Negative. Explain with the help of examples. 12. Select the correct choice : The work done by a force on a body will be positive if the : a. Body does not move b. Body moves perpendicular to the direction of applied force. c. Body moves along the direction of applied force. d. Body moves opposite to the direction of the applied force. 13. When a body moves in a circular path, how much work is done by the body? Give a reason. 14. A satellite revolves around the earth in a circular orbit. What is the work done by the force of gravity? 15. In which of the following cases, is the work being done and why? a. A man pushing a wall. b. A coolie standing with a load of 12 kgf on his head c. A boy climbing up a staircase d. A boy carrying a box on his head and sliding over a frictionless horizontal surface. 16. Give an example when the work done by the force of gravity acting on a body is zero, even though the body gets displaced from its initial position. 17. Is work a scalar or vector quantity? 18. One joule of work is said to be done when : a. a force of 1 dyne causes a displacement of 1 cm. b. a force of 1 dyne causes a displacement of 1 m. c. a force of 1 N causes a displacement of 1 cm. d. a force of 1 N causes a displacement of 1 m. 19. A boy of mass m climbs up a staircase of vertical height h. a. What is the force acting on the boy? b. What is the work done by the boy against the force of gravity? What would have been the work done, if he uses a lift in climbing the same height? 20. Define the term Power. 21. Write two mathematical expressions for power. 22. State and define SI unit of power. 23. Express SI unit of power in terms of MLT. 24. Name two bigger units of power and express them in watts. 25. What do you understand by the term horse power? Express this unit in SI system. 26. Differentiate between work and power. 27. Make the correct choice Kilowatt is the unit of : a. Work b. Power c. Force 28. Make the correct choice. One horse power is equal to : a. 647 W b. 746 W c. 476 W d. 764 W
29. Complete the following sentences. a. The SI unit of work is.. and of power is... b. Kilowatt is the unit of... c. Joule is the unit of... d. 1 joule =... ergs. e. 1 HP =...watts. 30. a. Define the term energy. b. Define the term potential energy. Give four examples of potential energy. c. Define the term kinetic energy. Give four examples of kinetic energy. 31. Derive an expression for potential energy. Or Derive an expression for potential energy of a body of mass m, placed at a height h above the earth s surface. 32. Derive an expression for kinetic energy. Or A body of mass m is moving with a velocity v. Derive the expression for the kinetic energy. 33. a. State the law of conservation of energy. b. How can you demonstrate the law by simple experiment? 34. State the energy changes which occur in following cases. a. Burning of coal. b. Petrol engine of running motor car. c. An electric cell in a circuit. 35. a. Give an example, when work done by a body is zero, even when body gets displaced from its original position on the application of force. b State the energy changes brought about by the following devices : i. Microphone ii. Steam engine iii. An electric bulb 36. A tennis ball and a table tennis ball have same momentum. Which of the two has more kinetic energy and why? 37. A man climbs a slope and another walks same distance on level road. Which of the two expends more energy and why? 38. What kind of energy is possessed in the following situations? a. A locked up spring of an air gun. b. A stone lying on the top of a roof. c. A fish moving in water. d. A horse running along a level road. e. Water stored in the dams. f. An electron spinning around the nucleus. g. A shooting arrow. h. A stone, in a stretched catapult. 39. Give one example in each case, when : a. Heat energy changes into kinetic energy. b. Kinetic energy changes into heat energy. c. Sound energy changes into electric energy. d. Electric energy changes into sound energy. e. Light energy changes into chemical energy. f. Chemical energy changes into light energy. g. Electric energy changes into mechanical energy. h. Mechanical energy changes into electric energy. i. Potential energy changes into electric energy. 40. State the energy changes which take place in the following cases : a. A bulb glows, when torch light is switched on. b. A car moves up a hill. c. A toy car spring is wound and the car is made to run on level floor. d. Water stored in the dams rotates the turbine connected to a dynamo. e. An air gun is loaded and then fired. f. A magnesium ribbon burns in air. g. A stone projected vertically upwards, returns back to the thrower. h. Water freezes in the freezing chamber of a fridge. i. Photographic film is exposed to the sunlight. j. Food is digested by animals.
41. What physical quantity does the electron volt (ev) measure? How is it related to SI unit of energy? 42. Complete the statement: 1 joule =... calorie. 43. Name the physical quantity which is measured in calorie. How is it related to SI unit of that quantity? 44. How much energy per second does a 40 watt bulb require? 45. What are two forms of mechanical energy? 46. What is meant by gravitational potential energy. 47. How is gravitational potential energy measured quantitatively? 48. Name the form of energy which a body may possess, even when it is not in motion. Give an example in support of your answer. 49. State the work-energy theorem. 50. A body of mass m is moving with a uniform velocity u. A force is applied on the body due to which its velocity changes to v. How much work is being done by the force? 51. A light mass and a heavy mass have equal momentum. Which will have more kinetic energy? Explain. 52. Name three forms of kinetic energy and give one example each? 53. What do you understand by conservation of mechanical energy? 54. Name two examples in which mechanical energy of a system remains constant. 55. A body falls freely under the action of gravity from the position of rest. Name the kind of energy it possessed i. At the point from where it fell, ii. While falling, iii. On reaching ground. 56. A body is thrown vertically upward. Its velocity keeps on decreasing. What happens to its kinetic energy as its velocity becomes zero. MACHINES 1. A block and tackle system has 5 pulleys. If an effort of 1000 N is needed to raise a load of 4500 N, calculate: a. Mechanical advantage b. Velocity ratio c. Efficiency of the system. 2. A machine is driven by a 100 kg mass that falls 8.0 m in 4.0 s. It lifts a load of mass 500 kg vertically upwards. a. What is the force in Newtons, exerted by the falling mass? b. What is the work done by 100 kg mass falling through 8.0 m? c. What is the power input to the machine? d. If efficiency of the machine is 75% or 0.75, what is the power output of the machine? 3. A cook uses a fire tong of length 28cm. to lift a piece of burning coal of mass 250g. If he applies his effort at a distance of 7 cm. from the fulcrum, what is the effort in SI unit? 4. Draw a lebelled diagram of a pulley system of four pulleys with two pulleys in each block. Indicate the direction of the load, effort and tension in the string. 5. State the class of levers and the relative positions of load (L), effort (E), and fulcrum (F) in each of the following cases a. a bottle opener b. Sugar tongs 6. Why is less effort needed to lift a load over an inclined plane as compared to lifting the load directly. 7. Pliers and scissors are levers of same order. a. Which amongst them has a mechanical advantage less than one? b. What is the usefulness of such a machine? 8. What is the relation between the MA & VR for a. An ideal machine b. Aa practical machine 9. Draw well labeled diagram of a single movable pulley system.