پاورپوینت علوم نهم مسافت، جابجایی، تندی، سرعت و شتاب (pptx) 28 اسلاید

دسته بندی : پاورپوینت

نوع فایل : PowerPoint (.pptx) ( قابل ویرایش و آماده پرینت )

تعداد اسلاید: 28 اسلاید

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Chapter 6A. Acceleration A PowerPoint Presentation by Paul E. Tippens, Professor of Physics Southern Polytechnic State University © 2007 The Cheetah : A cat that is built for speed. Its strength and agility allow it to sustain a top speed of over 100 km/h. Such speeds can only be maintained for about ten seconds. Photo © Vol. 44 Photo Disk/Getty Objectives: After completing this module, you should be able to: Define and apply concepts of average and instantaneous velocity and acceleration. Solve problems involving initial and final velocity , acceleration , displacement , and time . Demonstrate your understanding of directions and signs for velocity, displacement, and acceleration. Solve problems involving a free-falling body in a gravitational field . Uniform Acceleration in One Dimension: Motion is along a straight line (horizontal, vertical or slanted). Changes in motion result from a CONSTANT force producing uniform acceleration. The cause of motion will be discussed later. Here we only treat the changes. The moving object is treated as though it were a point particle. Distance and Displacement Distance is the length of the actual path taken by an object. Consider travel from point A to point B in diagram below: A B s = 20 m Distance s is a scalar quantity (no direction): Contains magnitude only and consists of a number and a unit. (20 m, 40 mi/h, 10 gal) Distance and Displacement Displacement is the straight-line separation of two points in a specified direction. A vector quantity: Contains magnitude AND direction , a number, unit & angle. (12 m, 30 0 ; 8 km/h, N) A B D = 12 m, 20 o q Distance and Displacement For motion along x or y axis, the displacement is determined by the x or y coordinate of its final position. Example: Consider a car that travels 8 m, E then 12 m, W. Net displacement D is from the origin to the final position: What is the distance traveled? 20 m !! 12 m,W D D = 4 m, W x 8 m,E x = +8 x = -4 The Signs of Displacement Displacement is positive (+) or negative (-) based on LOCATION . 2 m -1 m -2 m The displacement is the y-coordinate. Whether motion is up or down, + or - is based on LOCATION. Examples: The direction of motion does not matter! Definition of Speed Speed is the distance traveled per unit of time (a scalar quantity). v = = s t 20 m 4 s v = 5 m/s Not direction dependent! A B s = 20 m Time t = 4 s Definition of Velocity Velocity is the displacement per unit of time. (A vector quantity.) v = 3 m/s at 20 0 N of E Direction required! A B s = 20 m Time t = 4 s D= 12 m 20 o