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ICSE Grade IX Physics Demo Videos

Hello students we’re going to learn a new concept today that is we’re going to understand what is distance and what is displacement and what is the difference between this concept of distance and displacement so to understand this concept of distance and displacement let’s take a simple example we of course have a racing track as you can see and in this racing track  A is the initial point and of course there’s a final point that is B so you can see the flags and these flags indicate the final point of this racing track So A is the initial point B is the final point of course there’s a car and this car is moving along this racing track so let’s make this car move this car is going to go around the racing track of  course it’s going to go from the initial to the final position that is from A to B now what exactly has happened  this car has gone from A to B which means it has covered the path. the path covered is indicated by the green line and you can see that the car is covering a path of 250 meters between a and B so the Green Line is indicating the path covered and it is equal to 250 meters but obviously if this was not a racing track if it was you walking along it then of course you will not go around the racing track you would just walk on the grass and go from A to B which means that the distance between A to B can be covered by another path in this case of course the car went around the racing track so we say that this is the actual path covered by the car so the actual path covered by the car is called distance the car went from a to be around the track and therefore 250 meters in this case is counted as the distance but of course like i said if you had to walk from A to B you would just walk over the glass directly from A to B so the shortest distance between a to b is not around the track but straight to be that is hundred meters so the shortest distance between the initial and the final point is hundred meters and that exactly is displacement .displacement is the shortest distance between initial and final points so you see what is distance and what displacement let’s take another example again we have the racing track we again have the car but this time the car is going to go from a to a .it’s going to take a lap around this racing track so it’s going to start from a and of course after sometime it comes back to A. remember what was distance.  distance was the part covered by an object so the part covered by this object is of course the green line around the racing track so what is the distance the distance in this case is 500 meters because the part covered by the car is 500 meters so we say distance is 500 meters but what about displacement the shortest distance between the initial and final point is 0 because the initial point and the final point is the same that is  point a so the shortest distance between the initial and final point zero which means my displacement is 0 which means in this case even though the distance was not zero the displacement was zero so let’s write down and recap what we saw and the car goes from a to b the distance was 250 meters but the displacement was straight down that’s hundred meters but when the car went from a to a the distance was 500 meters and the displacement was simply 0 also note that the distance is always greater than the displacement and the distance will never be zero as long as the initial and the final points are not the same so that means the distance can never be less than displacement and distance is always greater than or equal to displacement so let’s write down how to represent this displacement, displacement we know is a vector because it has a magnitude in a direction how do you represent displacement it is represented by a straight line with an arrow using a convenience scale if I want to represent a 40-metre displacement towards the east so I’m just going to make a straight line PQ you can see there’s an arrow at q so it’s a straight line it has a arrow and this has to represent forty meter displacement towards the east of course I’ve drawn this line towards the east how will you make it represent 40 meters you simply say one centimeter is 10 meters so using one centimeter is representing 10 meters of course you can draw a 40-metre line to represent this displacement exactly what is happening P is the original or the initial position Q of course the final position and then we draw this line remember the length of the straight line gives you magnitude of the displacement and therefore in this case since the magnitude of the displacement is 40 Meter I will draw four centimeter line because one centimeter represents 10 meters so 4 centimeters gives me 40 meters so simply represent displacement you draw a straight line and you see that the length gives you the magnitude of the displacement finally let’s see what’s the distinguish between distance and displacement distance of course we know is the actual part followed by a body between the points in which it moves displacement is the shortest distance between the initial and final points of the movement distance is a scalar quantity while displacement is a vector quantity Scaler  of course we know has only magnitude and no Direction displacement is a vector with both magnitude and direction the third point is that distance is either equal to or greater than displacement we saw this in the racing track example displacement however it is either equal to or less than distance the fourth point is that distance is the length of the part Traversed  by the object in a certain time well as displacement is the distance by the object in a specified direction remember it’s a vector so specific direction is important again it is in a certain limit that is it should be the shortest distance it depends on the part followed by the object where as this depends on only the initial and final points and therefore does not depend on the path followed by the object finally distances always positive while displacement can be positive or negative depending on direction finally distance may be 0 even if displacement is zero distance may not be 0 like we saw displacement from A to A was 0 but in that case distance turned out to be 500 meters displacement it has to be 0 if the distance is 0 so we saw what distance  and what is a displacement and now we also know what is the difference between the two.

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2017-04-18T04:56:38+00:00 Categories: ICSE-IX||0 Comments
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