science class iv lesson 1 theory

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Equation of motion by graph

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MOTION Equations of motion by graphical method We already know about equations of motion when an object moves along straight line with uniform acceleration. We already know how to derive them but these equations can also be derived by graphical method. a. Equation for velocity time relation Consider the velocity-time graph of an object that moves under uniform acceleration as shown below in the figure 7. From this graph, you can see that initial velocity of the object is  u u  (at point A) and then it increases to  v v  (at point B) in time  t t . The velocity changes at a uniform rate  a a . Again from figure it is clear that time  t t  is represented by OC , initial velocity  u u  by OA and final velocity of object after time  t t  by BC. From graph as given in figure 7 it is clear that  B C = B D + D C = B D + O A B C = B D + D C = B D + O A . So we have  v=BD+u     ...
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Chapter 1 (Motion)

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Motion: If anybody changing its position with respect to time, then the body is said to be in motion. Or A body is said to be in motion if it changes its position continuously with respect to a stationary object taken as a reference point. For example: Let us consider two points A and B is far apart with each other, an object starts changing its position from A to B with time then the object is said to be motion.   Distance: The total length of the path travels by a body. Example: In the given image, Both of the figures represent the length of the path from A to B. And both are the  Distance.  It is denoted by “ s “, and it’s SI unit is m. Displacement: The minimum distance between the starting point and the ending point is known as Displacement . It is also denoted by “ s “, and it’s SI unit is m.   Example: In the above image, the first figure represents the  Displacement . And the second one represents the  Distance. One more Image related to Distance an...
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Mirror and it's types

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Mirrors A mirror is a reflective surface that does not allow the passage of light and instead bounces it off, thus producing an image. The most common mirrors are flat and called plane mirrors. These mirrors are made by putting a thin layer of silver nitrate or aluminium behind a flat piece of glass. When you place an object in front of a mirror, you see an image of the same object in the mirror. The object is the source of the incident rays, and the image is formed by the reflected rays. An image formed by reflection may be real or virtual. real image -  A “real” image occurs when light rays actually intersect at the image, and become inverted, or turned upside down. virtual image-  A “virtual” image occurs when light rays do not actually meet at the image. Instead, you “see” the image because your eye projects light rays backward. A virtual image is always upright. Differences between Real Images and Virtual Images S No. Real image Virtual image 1. A real...
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