RRB NTPC Exam 2016 will test you on Measurement of Quantities. In physics, quantities are categorized into either scalar or vector quantities.

## RRB NTPC Exam 2016 #Daily Infographic on General Science (Physics)

There are a lot of different mathematical quantities used in physics.

What is a scalar?

A scalar is a quantity that is fully described by a magnitude only. It is described by just a single number. Some examples of scalar quantities include speed, volume, mass, temperature, power, energy, and time.

What is a vector?

A vector is a quantity that has both a magnitude and a direction. Vector quantities are important in the study of motion. Some examples of vector quantities include force, velocity, acceleration, displacement, and momentum.

What is the difference between a scalar and vector?

A vector quantity has a direction and a magnitude, while a scalar has only a magnitude. You can tell if a quantity is a vector by whether or not it has a direction associated with it.

Example:

Speed is a scalar quantity, but velocity is a vector that specifies both a direction as well as a magnitude. The speed is the magnitude of the velocity. A car has a velocity of 40 mph east. It has a speed of 40 mph.

Interesting Facts about Scalars and Vectors

• Unit vectors are vectors with a magnitude of 1. They are used to define direction.
• The credit for inventing vectors is usually given to Irish physicist William Rowan Hamilton.
• Vectors and scalars are important in many fields of math and science.
• Vectors can be defined in two dimensional or three dimensional space.
• Vector graphics are sometimes used in computers because they can be scaled to a larger size without losing any image quality.

### How to Prepare General Science Section for RRB NTPC Exam

References: www.duckster.com

1. Sunil IH

In Relative physics, Time is something which is generally not specified in terms of vector.

Time is one of the four components of spacetime vectors; but as a vector component, it is not a relativistic invariant (which is why different observers measure time differently) and it does not transform under coordinate transformations as a scalar or a vector.

But if you still want to classify it, then In non-relativistic physics, time can be classified as a scalar.

In the definition of the vector “we have to give the information of the direction of motion to express that physical quantity”. But whenever we tell time to someone, we never say “it is 05:30 towards east or west, etc. or time is making this angle with the horizontal or vertical. We express the time without any direction so time is scalar.

Still let us try to negate it and suppose time is a vector quantity.Then it should obey vector law of addition. As you say it has only one direction, the resultant will always be an algebraic addition of the individual times like scalar. So by this property it also comes out to be a scalar.

Hope it cleared your doubt

2. hey thank you for the subtle explaination.. However i have a doubt …
is ‘Time’ a scalar or vector quantity ?