Physics is always understood in
terms of physical quantities.To understand a physical
quantities completely in a particular situation, it is enough for a physical quantity to have
only magnitude. This kind of physical quantities are called scalars. Maas and
length are some of the simple physical quantities who can be treated like
scalars.

But some physical quantities
demands both magnitude and direction to understand properly. For example if
somebody asks you how I have to come to your home?, you cannot say just drop
down at the bus terminal and walk 1 km ,you’ll reach my home. You have to say in
detail in which direction the person has to travel after getting down at the
bus terminal. Thus the situation demands not only magnitude but also the
direction in which he has to travel . This kind of physical quantities which need magnitude as well as direction to understand them clearly are being
called as vectors in physics.

As a whole we can divide all
physical quantities into two categories as scalars and vectors. Vector not
only need to have magnitude and direction but has also satisfy certain rules of
vector algebra.We are going to have a detailed look regarding the rules of
the vectors in the coming post. So when you specify a physical quantity as a
vector ,you have to specify not only its
magnitude but its direction .

Having a magnitude and direction
alone cannot qualify physical quantity to be treated as a vector. For example
time is a physical quantity who has both magnitude as well as a direction in
such a way that it always goes in a forward direction. But this doesn't satisfy
laws of vectors and hence it cannot be treated like a vector. Electric current
and pressure are some of this kind of physical quantities who have both
magnitude and direction but still has to be treated like scalars.

The vectors are generally
represented in terms of straight line
having a arrow head to it. The arrow head gives the direction of the
vector. There are different types of vectors.

The two vectors who are parallel
to each other are being treated as

**parallel vectors**are**like vectors**.
The two vectors who are
antiparallel to each other are called

**unlike vectors or anti parallel vectors**.
The two vectors who has same
magnitude and direction are treated as

**equal vectors**.**The negative vector**of a vector is a vector who has the same magnitude but the opposite direction of the original vector.

**A unit vector**is a vector who has only a magnitude of one unit but the direction of the original vector.

**Resolution of the vectors:**

A vector can be only in one
direction or in between the two axis. In this case the vector can be resolved
into components to identify the part of the vector along x-axis as well as the
y-axis. This kind of dividing the vector into parts is called as the resolution
of a vector. But when you add the two components of the vector you’re supposed
to get back your wards will vector. Then only we can say we have resolved the
vector properly. The components of the vectors are also vectors having a
specific direction.The components cannot have a direction that is different
from the original vector.

**Laws of vectors:**

Being a vector, a physical
quantity shall satisfy certain laws. The following are the some of the vector
laws of addition.

- Vector addition obeys committee to law.
- Vector addition obeys associate to law.
- Vector addition also obeys distributive law.
- Vectors also satisfy triangle law.

**Definition of triangle law:**

If three vectors are acting on a
point and the point is in equilibrium ,then the three vectors can be represented
as three sides of a triangle taken in an order.

**Parallelogram law:**

if two vectors are represented as
two adjacent sides of a parallelogram, then the resultant of the two vectors is
the diagonal of the parallelogram passing to the same point.

**Related Posts**

**Units and measurement**

**Writing dimensional formula**

**Errors and approximations**

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