# Scalar and vector quantities

Gray Vector Diagrams We use vector diagrams to visualize what is going on in a physical system. Even though we can work out most problems algebraically, a picture can help point out subtleties of a problem. The first step when solving any problem in physics is to draw a picture. The following diagram illustrates two points. A prototype of a vector is a directed line segment AB see Figure 1 that can be thought to represent the displacement of a particle from its initial position A to a new position B.

To distinguish vectors from scalars it is customary to denote vectors by boldface letters. Thus the vector AB in Figure 1 can be denoted by a and its length or magnitude by a. In many problems the location of the initial point of a vector is immaterial, so that two vectors are regarded as equal if they have the same length and the same direction.

This construction of the sum, c, of a and b yields the same result as the parallelogram law in which the resultant c is given by the diagonal AC of the parallelogram constructed on vectors AB and AD as sides. Also, it is easy to show that the associative law is valid, and hence the parentheses in 2 can be Scalar and vector quantities without any ambiguities.

If s is a scalar, sa or as is defined to be a vector whose length is s a and whose direction is that of a when s is positive and opposite to that of a if s is negative. Thus, a and -a are vectors equal in Scalar and vector quantities but opposite in direction. The foregoing definitions and the well-known properties of scalar numbers represented by s and t show that Inasmuch as the laws 12and 3 are identical with those encountered in ordinary algebra, it is quite proper to use familiar algebraic rules to solve systems of linear equations containing vectors.

## Vector algebra.

This fact makes it possible to deduce by purely algebraic means many theorems of synthetic Euclidean geometry that require complicated geometric constructions. The multiplication of vectors leads to two types of products, the dot product and the cross product.

The associative, commutative, and distributive laws of elementary algebra are valid for the dot multiplication of vectors. Also, since rotation from b to a is opposite to that from a to b, Figure 2: Since empirical laws of physics do not depend on special or accidental choices of reference frames selected to represent physical relations and geometric configurations, vector analysis forms an ideal tool for the study of the physical universe.

The introduction of a special reference frame or coordinate system establishes a correspondence between vectors and sets of numbers representing the components of vectors in that frame, and it induces definite rules of operation on these sets of numbers that follow from the rules for operations on the line segments.

If some particular set of three noncollinear vectors termed base vectors is selected, then any vector A can be expressed uniquely as the diagonal of the parallelepiped whose edges are the components of A in the directions of the base vectors.

 Products of vectors. Engineering Companies Scalar and vector quantities A study of motion will involve the introduction of a variety of quantities, which are used to describe the physical world. Examples of Vector and Scalar Quantity in Physics Acceleration Physics is a mathematical science. The underlying concepts and principles have a mathematical basis. A scalar quantity is a one dimensional measurement of a quantity, like temperature, or mass. A vector has more than one number associated with it.

In common use is a set of three mutually orthogonal unit vectors i. In this system the expression takes the form Figure 3: Also, the dot product can be written since The use of law 6 yields for so that the cross product is the vector determined by the triple of numbers appearing as the coefficients of i, j, and k in 9.

Such rephrasing suggests a generalization of the concept of a vector to spaces of dimensionality higher than three. For example, the state of a gas generally depends on the pressure p, volume v, temperature T, and time t. A quadruple of numbers p,v,T,t cannot be represented by a point in a three-dimensional reference frame.

But since geometric visualization plays no role in algebraic calculations, the figurative language of geometry can still be used by introducing a four-dimensional reference frame determined by the set of base vectors a1,a2,a3,a4 with components determined by the rows of the matrix A vector x is then represented in the form so that in a four-dimensional spaceevery vector is determined by the quadruple of the components x1,x2,x3,x4.

## BBC Bitesize - Higher Physics - Equations of motion - Revision 1

A particle moving in three-dimensional space can be located at each instant of time t by a position vector r drawn from some fixed reference point O. Since the position of the terminal point of r depends on time, r is a vector function of t. Its components in the directions of Cartesian axes, introduced at O, are the coefficients of i, j, and k in the representation If these components are differentiable functions, the derivative of r with respect to t is defined by the formula which represents the velocity v of the particle.

The Cartesian components of v appear as coefficients of i, j, and k in The rules for differentiating products of scalar functions remain valid for derivatives of the dot and cross products of vector functions, and suitable definitions of integrals of vector functions allow the construction of the calculus of vectors, which has become a basic analytic tool in physical sciences and technology.

Learn More in these related Britannica articles:1-D Kinematics. Lesson 1 - Describing Motion with Words; Introduction; Scalars and Vectors; Distance and Displacement; Speed and Velocity; Acceleration; Lesson 2 - Describing Motion with Diagrams.

In mathematics, physics, and engineering, a Euclidean vector (sometimes called a geometric or spatial vector, or—as here—simply a vector) is a geometric object that has magnitude (or length) and caninariojana.coms can be added to other vectors according to vector algebra.A Euclidean vector is frequently represented by a line segment with a definite direction, or graphically as an arrow.

The remainder of this lesson will focus on several examples of vector and scalar quantities (distance, displacement, speed, velocity, and acceleration). As you proceed through the lesson, give careful attention to the vector and scalar nature of each quantity. There are two types of vector multiplication (i) Scalar product and (ii) Vector product. Scalar product or Dot product of two vectors If the product of two vectors is a scalar, then it is called scalar product.

May 05,  · Vector quantities have two characteristics, a magnitude and a direction. Scalar quantities have only a magnitude.

When comparing two vector quantities of the same type, you have to compare both the magnitude and the direction. Check Your Understanding.

## 1 Distinguish between vector and scalar quantities, and give examples of each.

1. To test your understanding of this distinction, consider the following quantities listed below. Categorize each quantity as being either a vector or a scalar.

BBC Bitesize - GCSE Physics (Single Science) - Scalar and vector quantities - AQA - Revision 1