Physics · Motion In A Plane · NEET
Textbooks print a vector in bold, like A. But you cannot write bold by hand. So while writing, put a small arrow over the letter, for example A with an arrow on top. Both mean the same vector. In NEET options and questions you will see both forms, so treat bold A and A-with-arrow as identical.
The length of the arrow is drawn to scale and stands for the magnitude of the vector. A longer arrow means a larger value. Example: if you draw 1 cm = 5 m/s, then a velocity of 20 m/s is drawn as a 4 cm arrow. The two ends are the tail (start) and the head or tip (the pointed end, which shows direction).
The magnitude is a scalar. It is only a number with a unit and no direction. We write it as |A| = A. For example, if a force vector F has |F| = 10 N, the 10 N is a scalar. The direction part is separate. This is why magnitude alone can never fully describe a vector.
The bars |A| mean 'the magnitude of vector A', also called its absolute value. It is written in plain (non-bold) letters as A. So |A| = A just says: the size of the vector A is the plain number A. Whenever you see a plain letter (A, v, F) it is the magnitude; the bold or arrow form (A-vector) is the full vector.
Direction is shown two ways. In a diagram, the arrowhead points along the direction. In numbers, we give the angle the vector makes with a fixed axis, usually the x-axis, for example 30 degrees above the horizontal. So a vector is fully fixed once you state its magnitude and its direction angle.
Try the real previous-year questions from this chapter — each with the answer and a full solution.
A magnitude (a number with unit) and a direction. Missing either one means it is not a proper vector.
An arrow carries both pieces of information at once: its length gives the magnitude and its pointed head gives the direction, exactly what a vector needs.
Plain A is the magnitude (a scalar number). Bold A or A with an arrow on top is the full vector with direction included.
NEET rarely asks the notation directly, but every vector problem in Motion in a Plane, Laws of Motion and rotational motion uses this notation, so getting it right is a foundation for scoring.
