1.Physical quanitities are divided into two groups :
a.Scalers:
. The physical quantity which need only magnitude to describe it completely are called scalar quantities. Scalar quantities are added algebraically. Examples: mass, temperature, length, energy, etc.
b. Vectors:
The physical quantities which need both magnitudes as well as direction to describe to it completely are called vector quantities. The vector quantities follow law of vector addition i.e. the magnitude and direction varies with the direction of each vector. Examples: velocity, force, displacement, momentum, electric field, magnetic moment, etc.
Some physical quantities having magnitude as well as direction are called scalar quantities since these quantities do not follow the law of vector addition. These quantities are added algebraically. Eg. Electric current, presure, large angle etc.
· Vectors associated with rotation about axis are called axial vector examples Torque, Angular Velocity, Angular momentum, etc.
· Vector which terminate is called polar vector, momentum.
2. Representation of vector :
A vector quantity is represented by a straight line with arrow head. The length of straight line give the magnitude of vector and arrow head give the direction of the vector. The starting point O is called origin or tail of vector while the end point P is called head or terminus of vector. The vector is written by bold faced letter A.
3. Addition of vectors :
Vectors are added by following laws :
a. Triangle law of vector addition :
When two vectors are represented in magnitude and direction by two sides of a triangle taken in order then their resultant is represented in magnitude and direction by third side of same triangle in opposite order.
b. Parallelogram law of vector addition : Two vector represented in magnitude and direction by two adjacent sides of a parallelogram then the resultant is represented in magnitude and direction by diagonal of same parallelogram from same vertex.
Parallelogram law of vector addition is equivalent to triangle law of vector addition.
For magnitude : the magnitude of resultant is
R= √(P²+ 2PQCosθ + Q²)
For direction : ∝ be the direction of resultant
Tan∝ =Qsinθ/(P + Qcosθ)
a.Scalers:
. The physical quantity which need only magnitude to describe it completely are called scalar quantities. Scalar quantities are added algebraically. Examples: mass, temperature, length, energy, etc.
b. Vectors:
The physical quantities which need both magnitudes as well as direction to describe to it completely are called vector quantities. The vector quantities follow law of vector addition i.e. the magnitude and direction varies with the direction of each vector. Examples: velocity, force, displacement, momentum, electric field, magnetic moment, etc.
Some physical quantities having magnitude as well as direction are called scalar quantities since these quantities do not follow the law of vector addition. These quantities are added algebraically. Eg. Electric current, presure, large angle etc.
· Vectors associated with rotation about axis are called axial vector examples Torque, Angular Velocity, Angular momentum, etc.
· Vector which terminate is called polar vector, momentum.
2. Representation of vector :
A vector quantity is represented by a straight line with arrow head. The length of straight line give the magnitude of vector and arrow head give the direction of the vector. The starting point O is called origin or tail of vector while the end point P is called head or terminus of vector. The vector is written by bold faced letter A.
3. Addition of vectors :
Vectors are added by following laws :
a. Triangle law of vector addition :
When two vectors are represented in magnitude and direction by two sides of a triangle taken in order then their resultant is represented in magnitude and direction by third side of same triangle in opposite order.
b. Parallelogram law of vector addition : Two vector represented in magnitude and direction by two adjacent sides of a parallelogram then the resultant is represented in magnitude and direction by diagonal of same parallelogram from same vertex.
Parallelogram law of vector addition is equivalent to triangle law of vector addition.
For magnitude : the magnitude of resultant is
R= √(P²+ 2PQCosθ + Q²)
For direction : ∝ be the direction of resultant
Tan∝ =Qsinθ/(P + Qcosθ)
1 comments:
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