# 9th MOTION

Published on May 31, 2013

Author: allwynasir

Source: authorstream.com

SCIENCE : SCIENCE TOPIC - MOTION CLASS - IX MOTION-:: MOTION-: In physics , motion is a change in position of an object with respect to time. Motion is typically described in terms of velocity , acceleration , displacement , and time . [1] Motion is observed by attaching a frame of reference to a body and measuring its change in position relative to another reference frame. A body which does not move is said to be at rest , motionless , immobile , stationary , or to have constant ( time-invariant ) position. An object's motion cannot change unless it is acted upon by a force , as described by Newton's first law . An object's momentum is directly related to the object's mass and velocity , and the total momentum of all objects in a closed system (one not affected by external forces) does not change with time, as described by the law of conservation of momentum . As there is no absolute frame of reference, absolute motion cannot be determined. [2] Thus, everything in the universe can be considered to be moving. [3] PowerPoint Presentation: A moving car PowerPoint Presentation: REFERENCE POINT- It is defined as an stationary object with respect to which an object moves. DISTANCE-: ( i ) – the distance travelled by a body is the actual length of path covered by an moving body. (ii)Distance is a scalar quantity . (iii)Distance travelled by a moving body cannot be zero. PowerPoint Presentation: Displacement-: ( i ) The shortest distance covered between initial & final position of the body, along with direction is known as displacement. (ii) Displacement is a vector quantity. The final displacement of a body cannot be zero. PowerPoint Presentation: Uniform motion-: a body has a uniform motion if it travels equal distance in equal intervals of time no matter how small these intervals are. Graphical representation-: PowerPoint Presentation: NON UNIFORM MOTION- : A body has anon uniform motion if it travels unequal distances in equal intervals of time. GRAPHICAL REPRESENTATION SPEED-:: SPEED-: Speed of an object is the magnitude of its velocity (the rate of change of its position); it is thus a scalar quantity. The average speed of an object in an interval of time is the distance traveled by the object divided by the duration of the interval; the instantaneous speed is the limit of the average speed as the duration of the time interval approaches zero SPEED: SPEED (I) SPEED=DISTANCE TIME (II) SI UNIT OF SPEED= M/S. (III) Avg. Speed = total distance total time (iv) speed is scalar quantity. Velocity: Velocity velocity is the speed of an object and a specification of its direction of motion. Speed describes only how fast an object is moving, whereas velocity gives both how fast and in what direction the object is moving. [1] If a car travels at 60 km/h, its speed is known. However, if the car moves at 60 km/h to the north, its velocity has now been specified . PowerPoint Presentation: Velocity is a vector physical quantity ; both magnitude and direction are required to define it. The scalar absolute value ( magnitude ) of velocity is speed , a quantity that is measured in metres per second (m/s or ms −1 ) when using the SI (metric) system. For example, "5 metres per second" is a scalar and not a vector, whereas "5 metres per second east" is a vector. The rate of change of velocity (in m/s) as a function of time (in s) is acceleration (in m/s²) – how an object's speed or direction of travel changes over time, and how it is changing at a particular point in time. PowerPoint Presentation: Average velocity-: average velocity= U+V u is initial velocity 2 v is final velocity As a change of direction occurs while the cars turn on the curved track, their velocity is not constant . Acceleration: Acceleration In physics , acceleration is the rate at which the velocity of a body changes with time. [1] In general, velocity and acceleration are vector quantities , with magnitude and direction [2][3] , though in many cases only magnitude is considered (sometimes with negative values for deceleration). Acceleration is accompanied by a force , as described by Newton's Second Law ; the force, as a vector, is the product of the mass of the object being accelerated and the acceleration (vector). The SI unit of acceleration is the metre per second per second (or "meter per second squared", m/s 2 ). PowerPoint Presentation: Acceleration = change in velocity Time taken for change = Final velocity- Initial velocity Time taken Or, a = v-u v is final velocity t u is initial velocity Equations of motion: Equations of motion ( i ) v = u+at (ii) s = ut+1/2at (iii) v = u +2as THANK YOU : THANK YOU

31. 05. 2013
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31. 05. 2013
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31. 05. 2013
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31. 05. 2013
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31. 05. 2013
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31. 05. 2013
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31. 05. 2013
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31. 05. 2013
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31. 05. 2013
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