• We see the moving vehicles br • Walking people br • Running trains br • If I ask you how fast or slow these objects are moving, can you tell me? br • Cars are fast (CU kids telling) br • Walking is slow (CU kids telling) br • Train is very fast (CU kids telling) br • But if we want to measure accurately how fast and slow these machines are we’ve to know their speed. br • Speed is “the distance traveled in unit time” br • Its symbol is v br • Formula of speed is measured by dividing total distance covered in unit time. br • Mathematically its is represented as v is equal to d over t br • Here v is representing speed, d is used for distance and t is used for time. br • Unit of speed is meter per second. br • Speed is a scalar quantity. br • Let’s take an example br • Suppose here’s a stop-watch and here’s a bi-cycle on clean road. br • It moves from this tree to that house. br • Look it covered 200 meters in 5 sec. br • So its speed is 40msec.