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Unit Vector Formula

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Last updated date: 12th Jul 2024
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Vector Unit Formula

To understand the concept of the unit vector formula in physics, one must be clear regarding what a vector is.

A vector is a quantity that has magnitude along with the direction.

A vector is defined numerically by an arrow over the letter. And the vector's value is always represented by the mod.

To comprehend the unit vector formula, everyone must first actually recognize what a unit vector is.

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Unit Tangent Vector Formula


Given, function f(x)=x3+x+x2 which is differentiable in x.

Therefore, f'(x)=(3x2) +1+2x

f'(x) is called the velocity vector.

The tangent vector equation is then the unit vector in the form of the velocity vector and is used by the unit tangent vector equation to calculate the vector's length.


||f'(x)||=√[(9x4) +1+4x2]


unit tangent vector T(x)=f'(x)/||f'(x)||.... (3)

= ((3x2) +1+2x)/√[(9x4) +1+4x2]

Principal Unit Normal Vector Formula

The normal vector to a surface, also generally known as the "normal," is a vector that is orthogonal to the surface at a given point.

There is an infinite number of perpendicular vectors to a vector in space. Our primary objective is to select a special vector right angles to the unit tangent vector.

Let f(x) be a differentiable vector-valued function and let T(x) be the unit tangent vector. Then,

where from equation (3),



the unit normal vector formula is, N(x) =T′(x)/||T′(x)||

As directly compared to the formula for the unit tangent vector, when we consider the unit tangent vector as a vector-valued function, then the principal unit normal vector N(x) is the unit tangent vector of the unit tangent vector function.

Solved Examples

Example 1:


There is a vector a= (1,0).

To find the magnitude of the given vector, we use the formula,

|a|= √(x2+y2+z2) ......(1)

Using the magnitude of unit vector formula (1),

|a|= √ (12+0) =√1=1

Therefore, a is a unit vector.

Example 2:


There is a vector b= (2, 3).

To find the magnitude of the given vector, we use the formula,

|b|= √(x2+y2+z2) ......(1)

Using the magnitude of unit vector formula (1),

|b|= √ (22+32)

= √13

Now, √13≠1.

Hence, from the above calculations, we can conclude that,

a is not a unit vector.

Formula To Find Unit Vector

â = a/|a|.......(2)

   = (x,y,z)/√(x2+y2+z2)

For example, a= (12,4,3)

Then, using (1),

|a|= √ ((122) +(42) +(32))

      = √144+16+9 = √169=13

Substituting, |a| in vector unit formula (2),

â = (12,4,3)/13

  = ((12/13), (4/13), (3/13))

FAQs on Unit Vector Formula

Q1. What is a Unit Vector?

Answer: A vector in a specified direction of magnitude equal to 1 is referred to as a unit vector.

The unit vector is always a dimensionless quantity. Commonly, unit vectors are used to represent a particular direction.

Q2. Why Do We Use Unit Vectors?

Answer: To convert any given vector into a unit vector, we use the unit vector formula.

In the unit vector equation, the given vector is divided simply by the vector's magnitude to find the unit vector.

The magnitude value of a vector is a scalar.

Such that the entire vector can be calculated by multiplying the unit vector in the direction of that vector by the magnitude value of the vector.