1. Physical quantities which can completely be specified by a number (magnitude) having an appropriate unit are known as Scalar Quantities. Scalar quantities do not need direction for their description. Scalar quantities are comparable only when they have the same physical dimensions. Motion in a Plane Scalar Quantities

2. Two or more than two scalar quantities measured in the same system of units are equal if they have the same magnitude and sign. Scalar quantities are denoted by letters in ordinary type. Scalar quantities are added, subtracted, multiplied or divided by the simple rules of algebra. Motion in a Plane Scalar Quantities

3. Work, energy, electric flux, volume, refractive index, time, speed, electric potential, potential difference, viscosity, density, power, mass, distance, temperature, electric charge, electric flux etc. Motion in a Plane Examples

4. Physical quantities having both magnitude and direction with appropriate unit are known as vector quantities. vector quantities are expressed by using bold letters with arrow sign such as: vector quantities added, subtracted, multiplied or divided by the rules of trigonometry and geometry. Motion in a Plane Vector Quantities

5. Velocity, electric field intensity, acceleration, force, momentum, torque, displacement, electric current, weight, angular momentum etc. Motion in a Plane Examples

6. "If two vector quantities are represented by two adjacent sides or a parallelogram then the diagonal of parallelogram will be equal to the resultant of these two vectors." According to the parallelogram law of vector addition: Explanation Consider two vectors Let the vectors have the following orientation Motion in a Plane Parallelogram Law of Vector Addition

7. Parallelogram of these vectors is According to parallelogram law: Motion in a Plane Parallelogram Law of Vector Addition

8. Magnitude or resultant vector can be determined by using either sine law or cosine law. Motion in a Plane Magnitude of Resultant Vector

9. Consider two vectors  and acting in the directions as shown. Draw representative line OA of vector and line AB of vector such that the tail of coincides with the head of vector. GRAPHICAL METHOD Motion in a Plane Addition and Subtraction of Vectors

10. Join 'O' and 'B'. OB represents resultant vector of given vectors and. Motion in a Plane Addition and Subtraction of Vectors