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Std 7th physics, Solutions- Exe. 2.1, A. Fill in the blanks, 1. Rectilinear, 2. Rotatory, 3. Translatory, 4. Oscillatory, 5. Vibratory, B. Correct the statements/, 1. Periodic – translatory, 2. rectilinear – curvilinear, 3. rest - motion, 4. oscillatory – vibratory, 5. periodic – non periodic, C. True or false., 1. True, 2. False, 3. False, 4. False, 5. True, D. Tick the option., 1. D, 2. B, 3. B, 4. C, 5. D, E. Match the pair., 1. D, 2. E, 3. B, 4. C, 5. A
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Study questions, 1., a. Rest – the body is not changing their place with respect to time., i. If you put stone on table, that will remain at rest., b. Motion - the body is changing their place with respect to time., i. Car is moving on road so it is in motion., 2., a. a linear motion in which the direction of the velocity remains, constant and the path is a straight line. Example – a ball is, moving on ground straight., b. motion in which the direction of the velocity of a body is variable, and the path of the body is a curved line. A stone is throne, upward with some angle., c. Rotatory motion is the motion that occurs when a body rotates, on its own axis. Wheel of cycle is moving in rotatory motion., 3., a. Oscillatory motion is defined as the to and fro motion of the body, about its fixed position. Oscillatory motion is a type of periodic, motion. Examples of oscillatory motion are vibrating strings,, swinging of the swing etc., b. When a part of the body remains fixed and the rest part moves, to and fro, that is called vibratory motion. For example: when, humans breathe, their chest expands and contracts., c. motion repeated in equal intervals of time. Periodic motion is, performed, for example, by a rocking chair, a bouncing ball,, d. The motion which does not repeat itself after regular interval of, time is called non-periodic motion. Examples : A footballer, running on a field, application of brakes in a moving vehicle., 4. Drill machine, 5., a. Curvilinear motion, b. Rectilinear motion, c. Rotatory motion
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d., e., f., g., , Oscillatory motion, Vibratory motion, Periodic motion, Non periodic motion