Understanding Speed

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