1. Physical world and measurements

2. Basic/ Fundamental quantities 1. Length 2. Mass 3. Time 4. Temperature 5. Electric current 6. Luminous intensity 7. Amount of substance

3. Derived Quantity The quantities derived from the fundamental quantities are called derived quantities. Eg:- speed, acceleration, momentum, force, work, impulse, Power, pressure etc.

4. Units CGS system MKS System FPS System Cm, gm and sec is the lower unit of measurement system. Metre, Kg and Sec is the higher unit system of measurement. FPS is the British system of unit.

5. Dimension Dimension of a physical quantity is the power to which a physical quantity is raised to obtain derived quantity. 1.Length ---[L] 2.Mass---[M] 3.Time---[S] 4.Temperature—T] 5.Electric current—[A] 6.Luminous intensity—[CD] 7.Amount of substance—[m]

6. Dimension of velocity [v] =[L/T] Dimension of acceleration [a] = [ L/T2] Similarly all the quantities can be expressed as powers of various fundamental quantities.

7. Applications of dimension 1) To check the correctness of the equation 2) To formulate the equation Check the correctness of the equation v = u + at [v ]= [u + at] [L/T] = [L/T] + [L/T] Dimension of LHS is equal to dimension of RHS. Hence the equation is dimensionally correct.