## Wednesday, February 22, 2017

### Parallelogram law and addition of vectors Video Lesson

We are going to deal about parallelogram law of vectors and using the law to find the addition and subtraction of the given vectors. Vector is a physical quantity that has both magnitude and direction. When we add scalars, we only need to worry about their magnitude,  But adding vectors is little complicated when compared with scalars. We can add them using a basic graphical method. Here we need to shift the second vector in parallel so that the magnitude and direction remains same. Then the tail of the first vector has to be joined with head of second vector to get the resultant of the two vectors. This is little graphical and performing this method is lengthy process when multiple vectors are involved.

The alternate method to add the two vectors is algebric method using parallelogram law of vectors. According to the law, if two vectors are represented as two adjusent sides of a parallelogram starting from the same point,  then the resultant of the two vectors is the diagonal of the parallelogram and its direction also can be found as shown in the video below.

Resultant of two vectors

We can apply the above mentioned law for different cases. What will be the resultant of the two vectors depends on the magnitude of the two vectors, the angle between them. Here in the below video, we are solving different basic possible cases and we have found the resultant of the given two vectors using the parallelogram law of the vectors.

We also would like to consider the addition of the two vectors using algebric method. Here we represent the vectors with components along the X,Y and The Z axis. When we are adding the vectors, we add the respective components and the find the resultant vector and its direction as shown in the video below.

Relative Velocity

Relative velocity is different from resultant velocity. Relative velocity is the comparative velocity of one body with respect to the other.  A body will have relative velocity only when it has effective displacement when compared with the other body. In the following video, it is explained the way of measuring the relative velocity in brief.

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