Port Said International Schools Better Education for Future Generations Science Department Grade: 9 Unit 1 – Lesson 2 Name: ………………………………………. Date: …………………………………………………… Complete the following statements: 1. The speed measuring units are …………….. and …………………, while acceleration measuring unit is ……………….. 2. When the speed of a car increases the motion is described as ……………… motion, while when the speed decreases the motion is described as ……………… motion. 3. If the body starts moving from the rest the initial speed = ………………. 4. The acceleration is described as the change in …………………. in one ………….. 5. Acceleration increases if the speed of an object ………………, while it decreases when the object’s speed …………….. 6. The graph for an object moving with regular (uniform) acceleration is represented by ……………… on the X axis and ………………. On the Y axis. Choose the correct answer: 1. On recording the results of an experiment in which an object moves, the results were recorded as follows: the object moves at ……………….. (increasing speed – uniform acceleration – uniform speed – irregular speed) Distance (meter) 10 20 30 Time (sec.) 1 2 3 2. On recording the results of an experiment in which an object moves, the results were recorded as follows: the object moves at ……………….. (increasing speed – uniform acceleration – zero acceleration – irregular speed) Distance (meter) 10 20 30 Time (sec.) 1 2 3 3. Which of the following (speed – time) graphs represents the movement of an object that moves with constant speed. 4. When an object’s speed increases, the movement is described as (uniform speed – decelerating motion – zero acceleration – accelerating motion). 5. The decelerating motion means that the (object’s speed decreases – object’s speed increases – object’s speed is constant – object is at rest). 6. The amount of change in speed at time unit is (velocity – displacement – acceleration – distance). 7. Acceleration measuring unit is (m/s – m.s – m/s2 – m.s2). 1 Port Said International Schools Better Education for Future Generations Science Department Grade: 9 Unit 1 – Lesson 2 8. When the object moves at constant (uniform) speed, this means that ……………… a. It moves at zero acceleration. b. It moves at constant acceleration. c. It covers equal distances at unequal intervals. d. It covers unequal distances at equal intervals. 9. A car moves with speed 30 m/s, then the speed changes to 60 m/s after 3 seconds, the acceleration = (10 m/s – 10 m/s2 – 20 m/s2 – 30 m/s) …………………………………………………………………………………………….. ……………………………………………………………………………………………… ……………………………………………………………………………………………… ……………………………………………………………………………………………… 10. The ratio between final speed and initial speed for an object that moves with acceleration motion is (more than 1 – less than 1 – equals 1 – equals 0). 11. When the final speed of a moving object is less than the initial speed the object’s motion is described as (uniform speed – accelerating speed – uniform acceleration – decelerating motion). 12. Which of the following graphs represents the motion of a body at uniform acceleration? …………….. Study the following graphs and describe the motion of the body in each of the following graphs: A: …………………………………………………………………………………………… B: …………………………………………………………………………………………… C: …………………………………………………………………………………………… 2 Port Said International Schools Better Education for Future Generations Science Department Grade: 9 Unit 1 – Lesson 2 Which of the following graphs represents the movement of an object at: a. Increasing acceleration: …………………………….. b. Zero acceleration: ………………………………….. c. Decreasing acceleration: …………………………… The following table shows the results of an experiment of a car starts moving from rest: Distance (m) 5 10 15 20 Time (sec.) 1 2 3 4 3 Port Said International Schools Better Education for Future Generations Science Department Grade: 9 Unit 1 – Lesson 2 a. Draw the graph which represents these results. b. Does the car move a regular speed? Why? ……………………………………………………………………………………………… ……………………………………………………………………………………………… ……………………………………………………………………………………………… c. Calculate the speed of the car. ……………………………………………………………………………… ……………………………………………………………………………… ……………………………………………………………………………… d. The acceleration = ……………………. m/s2 From the opposite graph which represents the motion of a bicycle: a. What is the maximum speed of the bicycle? ……………………………………… b. What is the kind of motion during the phase BC? …………………………………….. c. When the driver of the bicycle started to use the breaks? …………………………………….. d. Which part represents: a. Accelerating motion? ……………………………………… b. Decelerating motion? ……………………………………… Examine the graph and calculate (find) the following: 1. The distance travelled by the object during the first four seconds. ………………………………………….. …………………………………………. …………………………………………. …………………………………………. 2. The maximum speed reached by the object during its movement. …………………………………………. 3. The acceleration in which the object moves in the last four seconds? What is the kind of this acceleration? ……………………………………………………………………………………………… ……………………………………………………………………………………………… 4
