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Class IX – Physics Holidays Home Work (Session 2011-2012) Multiple Choice Questions (Type A)______________________________________________________________________ 1. An object travels 16 m in 4s and then another 16 m in 2s. The average speed of the object is (a) 5.33 m/s (b) 4 m/s (c) 8 m/s (d) 5 m/s 2. An cyclist travels a distance of 6 kilometers in 10 minutes. His speed in meter per second is (a) 36 m/s (c) 10 m/s (a) 100 m/s (b) 3.6 m/s 3. Which of the following can be zero when the particle is in motion for sometime? (a) Displacement (b) Distance covered (c) Speed (d) None of these 4. The ratio of magnitude of displacement to distance is (a) always less than one (b) always equal to one (c) always more than one (d) equal to or less than one 5. The velocity-time graph of a motion starting from rest with uniform acceleration is a straight line (a) parallel to time axis (b) parallel to velocity axis (c) not passing through origin (d) having none of the above characteristics 6. A car accelerates from rest at constant rate for the first 10 s and covers a distance x. It covers a distance y in the Next 10 second at the same acceleration. Which of the following is true ? (a)x = 3y (b}y = 3x (c) x = y (d)y = 2x 7. While going from home to the office, a person covers a distance of 3 km at a speed of 7.5 km/h. H comes Comes back home covering the same distance at a speed of 6 km/h. The total time taken is (a) 54 minutes (b) 0.9 minutes (c) 900 minutes (d) 0.75 h 8. The graph which represents the object moving under constant acceleration is 9. An aeroplane starting from rest accelerates uniformly and covers on the runway a distance of 1000 m in 10 The final speed attained by the aeroplane is (a) 72 m/s (b) 100 m/s (c) 20 m/s (d) 200 m/s 10. A boy starts moving from a point 'A' along a circular path of radius 'R' and Reaches the point ‘B’ as shown in the figure. The displacement in this case is (a) rrR.j2 (b) R (c).j2R (d) 2R Multiple Choice Questions (Type B)_________________________________________________________________ 1. Read the following statements: A particle moves with uniform velocity. A particle moves with uniform velocity. P: Its speed is zero Q: Its acceleration is zero R: Its acceleration is opposite to the velocity S: Its speed may be variable Select the correct alternative: (a) P and S are false (b) P, R, S all three are false (c) only R is true (d) none of the statements are true 2. Read the following statements: A: Displacement has both magnitude and direction B : Displacement can be represented geometrically C: Magnitude of displacement is always less than the distance D: Displacement is always positive. Select the correct alternative: (a) All four are correct (b) A,B,C are correct (c) Only C is incorrect (d) C,D, are incorrect whereas A, B correct statements 3. Read the following statements: For an object in motion: P: If its speed changes, its velocity must change Q: If its velocity changes, its speed must change R: If its speed changes, but direction of motion does not change, its velocity may remain constant S: If its velocity changes, speed may not change, and it must have some acceleration Choose the correct alternative: (a) only rand Q are correct (b) all the statements are correct (c) P and S are correct but Q and R are incorrect (d) only P is correct 4. Two balls of different masses are dropped from the same point at the same time. If value of g is constant And air resistance is neglected; then A: The heavier ball reaches the ground before the lighter one does B: Both balls reach the ground at the same time C : The heavier ball hits the ground with a higher speed D: Both the balls reach the ground with the same speed Choose the correct alternative: (a) only B is correct (b) none of the above statements are correct (c) only Band D are correct statements (d) only C is correct 5. Read the following statements: X: During uniform circular motion of a particle the direction of velocity changes continuously but its Magnitude remains constant. Y: During uniform circular motion, direction of motion is always tangent to the circle at every point. Z : The motion of a satellite in a circular orbit around the Earth, is an example of an accelerated motion Choose the correct alternative: (a) only X is correct (b) only Z is correct (c) all the three are correct (d) X and Yare correct True or False? _________________________________________________________________________________ State whether the following statements are True or False: 1. When a particle is in motion, its velocity is always in the direction of motion. _________________ 2. When a particle moves with uniform velocity, its displacement always increases with time. _________________ 3. A body can have zero velocity with non-zero acceleration. _________________ 4. A ball thrown vertically uptakes the same time to go up and come down. _________________ 5. The slope of v-t graph gives displacement. __________________ 6. The x-t graph can take sharp turn. __________________ 7. The displacement-time graph always shows the true path of the moving particle. __________________ 8. In a free fall, the initial velocity of a body is always zero. __________________ 9. A heavy body falls at a faster rate as compared to a lighter body. __________________ 10. The area under the velocity-time graph between t1 and t2 gives the displacement (x 2 - X I) between the two instants. __________________ Fill in the blanks________________________________________________________________ 1. The displacement of a body may be __________,_____________ or zero, depending upon the initial and final position of the moving body and its direction, while the _______________of displacement is always positive. 2. The displacement of a body becomes zero when it moves along a __________________________path. 3. For _____________________motion in one direction, speed and velocity are similar. 4. When a body moves with uniform velocity, its _____________________________will be zero. 5. The distance travelled by a body in certain time is equal to ________________________the under the velocity-time graph for the given time interval. 6. The 51 unit of acceleration is ______________________________ 7. In successive time intervals if the average velocities of a particle are equal, then the particle must be moving with __________________________velocity. 8. The magnitude of average velocity is always ____________________________than or equal to the average speed. 9. The three equations of kinematics are specifically derived ______________________________for motion. 10. In uniform circular motion velocity remains constant in _______________but varies in ___________________. Graphs Directions: We have seen that newspapers, magazines, etc., present information in various forms of graphs to make it interesting. Graphs are the pictorial or visual form which help in analytical interpretation of data in science and mathematics. There are different forms of graph-line, bar and pie. To study motion, we usually prefer line graph. Figure shows the distance-time graph of three students X, Y, Z. Study the graph and answer the following questions: Which of the three is travelling the fastest? _____________________________________________________ _____________________________________________________ Are all the three ever at the same point on the road? How far has Z travelled when X passes Y ? How far has Y travelled by the time it passes X? If Was A… ? Worksheet (Activity-Role Play ) Pretend you are a distance-time graph for the remaining questions. 1. What is your nature for uniform motion of An object? _______________________________________________ _______________________________________________ _______________________________________________ _______________________________________________ 2 What is your nature for non-uniform Motion? _______________________________________________ _______________________________________________ _______________________________________________ _______________________________________________ 3 what can you say about the motion of an object for which your shape is an straight line parallel of the time axis? _______________________________________________ _______________________________________________ _______________________________________________ _______________________________________________ 4 what does your slope indicate ? _______________________________________________ _______________________________________________ _______________________________________________ _______________________________________________ 5 your shapes for two moving bodies A and B are given below which of the two travels faster? Do A and B have the same speed ? _______________________________________________ _______________________________________________ _______________________________________________ _______________________________________________ _______________________________________________ Group Creative Writing____________________________________________________________________________ Topic: Educational trip Directions: Suppose you are travelling from New Delhi to Jaipur by road on an educational trip. Write a story about you trip using the flowing words: Bus motion speedometer odometer Uniform motion non-uniform motion speed average speed Velocity distance displacement acceleration Time taken kilometers hours On our educational trip we travelled by road in a bus. On the road we found mile stones indicating kilometers. ________________________________________________________________________________________________ Across An instrument by which the distance travelled by a car is measured. (8) An instrument by which instantaneous speed of a car is determined. (11) The decrease in velocity of a body with time. (11) A moving body travels unequal distances in equal intervals of time irrespective of direction. (10,5) The shortest distance between the initial and final position of a moving body in a particular direction. (12) Down: A body which changes its position with respect to a fixed point. )6) A body which does not change its position with respect to a fixed point. (6) The displacement of a body in unit time. (8) The rate of change of velocity with time. (12) The distance travelled by a body in unit time. (5) The ratio of the total distance travelled by the body to the time taken by it to cover that distance. (7,5) Roll No – 1 to 18 Make a PPT presentation on any one of the following topics:- 1. LAW OF MOTION 2. ARCHIMEDE’S PRINCIPLE 3. APPLICATIONS OF ULTRASOUND 4. TYPES OF MOTION WITH EXAMPLES 5. FORMS OF ENERGY