Vectors – what are they , How to Add, Subtract, Multiply…..

Physics chapters are full of vectors and the word “vector” will come in front of us , every now and then. So, it is critically important to get over the fear of vectors, and to naturally be able to play with them, in any kind of situation . As you will see soon , we’ll make it easy.

1) A vector is any physical quantity which has got a DIRECTION plus MAGNITUDE.

2) Physical Quantities that have above two star things are :- Weight, all types of Forces, Displacement, Velocity, Acceleration, Current, Magnetic Field, Electric Field,  and so on. All are VECTORS.

3) Physics Quantities that have Magnitude but do NOT have a Direction are :- Mass, Distance travelled, Speed, Time, Specific Gravity, Density, Electrical Resistance…. => these have magnitude but no Direction. So they are called SCALARS. They are equally important as Vectors. Imagine TIME ! It has no direction in physics and reality , i.e. we can never never reverse the direction of time.

4) One good thing is that Vectors are always drawn as a straight line arrow . The rules of addition, subtraction , multiplication can all be done on vectors. Vectors at any point on a Graph, show what is the TANGENT at that point. So, if we have a straight line graph on a X-Y axis , it means there is only one Resultant Vector, and its SPILT parts, its sub-vectors so to speak are arrows from the Origin to the X-axis value and Y-axis value.

What happens for Curved Graphs ? No problem. At any point on the graph, the tangent shows the Resultant vector of the sub-vectors lying along x-axis and Y-axis. At some other point on the same graph, the Tangent can be inclined in another direction, it is made by another combination of sub-vectors lying on X-axis and Y-axis, but having different magnitudes. That’s how curved graphs can be thought of as consisting of an infinite number of Resultant vectors at each of the infinite points along the curve. Overall, we see a smooth curve.

Video – Vectors Basics, Look & Feel     

See videos on various types of graphs in sections below.