LESSON 1 11 2021 VECTORS IN TWO DIMENSION scalar – a physical quantity that has magnitude (size), but no direction; examples are time, mass, length, area,volume, energy, charge,pressure and temperature vector – a physical quantity that has both magnitude and direction; examples are force, velocity and electric field resultant vector – a single vector that indicates the magnitude and direction of the combined effect of two or more vectors VECTORS THAT ACT ALONG THE SAME LINE • We can represent a vector graphically by drawing a straight line with an arrow head. The length of the line represents the magnitude of the vector and the arrow head points in the direction in which the vector operates. .We can represent one or more vectors in a drawing using arrows. Such a drawing is called a vector diagram. .When we represent or add vectors along the same line, we choose a particular direction as positive. The opposite direction is then negative. .The combined effect of two or more vectors is called the resultant. .When we represent vectors graphically in a vector diagram, we indicate a reference direction. Each vector must have an arrowhead. .When we add vectors that act along the same straight line algebraically, we clearly state the direction chosen as positive. .We always indicate the resultant vector by the number that represents its magnitude, the correct unit and the correct direction. ADDITION OF VECTORS THAT ARE PERPENDICULAR TO EACH OTHER THE CARTESIAN PLANE. The Cartesian plane is a reference system where two axes are drawn at right angles. The horizontal axis is called the x-axis and the vertical axis is called the y-axis. The intersection of the axes is called the origin. Directions to the right and upwards of the origin are positive. The opposite directions are negative . The diagram (a) above shows two forces, 1 N and 2N, that act vertically upwards on a box. At the same time, two forces of 2 N each act in the same horizontal direction. The resultant horizontal component is : F X=2 N + 2 N = 4 N The resultant vertical component FY = 1N + 2N = 3N Diagram (b) shows how to do this graphically. HOMEWORK 1 HOMEWORK 2
