Asked By :

Amilal S.Posted: Mon 07 September 2015

what is vector?

IIT JEE

Vector is a quantity which has both magnitude as well as direction. For example, force, velocity are some vector quantities. They have some magnitude and have direction. There are some quantities which have only magnitude, they are called scalar. Feel free to reach out for any other assistance. Regards, Vinay Sogani

09 Sep 2015 14:11

IITB Alumni, IIT JEE Score - Physics - 115/162, Mathematics - 130/162

Any quantity which has both magnitude and direction. There are more abstract definitions of vectors and vector spaces in higher Mathematics, but this is enough for IIT JEE.

09 Sep 2015 00:32

Mathematics Tutor, 4 plus years of experience, 3rd Ranker at Ramanujan Institute of Advanced Mathematics

Hi Amilal Saini. Sorry for the late reply. Well, in short "vector is directed line segment". Now, let me explain what is that. Visualize that you are at the origin in the coordinate plane XY-plane. Now suppose I give you two different type of instructions: (1) Move 5 unit distance (in the direction whatever you want to choose) and (2) Move 5 unit distance along X axis in positive side. Now understand the difference. In the first case, I asked you to move on 5 unit distance (also in 2nd one) but the choice of choosing the direction was not given by me. It was completely your freedom. Which means in the instruction no. 1, we are concerned about only the movement and its distance BUT NOT THE DIRECTION. Whereas in the second one, I asked you once again move 5 unit distance but this time a specific direction was given by me and you had to follow that. I asked " Move along x-axis in positive side with 5 unit distance". Well, that the part "along X-axis in positive side" made the specific choice of "direction" of movement. So instruction 1 is related to something called scalar quantity whereas instruction 2 is related to "vector quantity". So this particular example tells us that, when an object is moving some distance but the direction is given, we say the object is a scalar (which has only a particular value but no direction) whereas when an object moves some finite unit distance along some specific direction, it is called vector. So remember always, scalar has no direction but only values. Whereas vector has values as well as direction. Time is scalar quantity because it does not matter in which direction it is moving, we just bother about its value. Displacement is another example of scalar quantity because once again here also we do not bother about the direction of movement, we care about the distance travelled only. Whereas velocity is vector quantity because not only we have to find its value, but also its direction is important. Confused? Say visualize a boat in river. Water is flowing. Now if the boat is moving in the direction of the flow of water, the velocity of boat will be much faster. Whereas if the boat is moving in the opposite direction, this time because of the resistance of flow of water, velocity of boat will be much slower. Do you see now that direction plays an important role in the movement of the boat? This is why velocity is vector. There are plenty of examples are available regarding vector and scalar. You can find on your own. I hope my answer has answered you well, if not, let me know. With regards, Anjan Debnath

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