Lecture Notes: Speed and Ratio

Basic Concepts of Speed

• What is speed
  • The act of covering a distance in a certain time.
  • Example: Moving 5 centimeters in 1 second → speed.
  • Speed is a combination of time and distance.
  • Standard units of speed
    • Example: 5cm per second or 5cm/s.

Unit Conversion

• Conversion of units
  • It is necessary to convert between speed per second, per minute, and per hour.
  • Example: Converting speed per second to per minute, or from per minute to per hour.

Interpreting Speed as Length

• Image of Speed
  • Grasping speed as the image of length enhances understanding.
  • Moving 5 centimeters in 1 second → consider this as length.
  • Example: A turtle moves 5cm in 1 second.

Conversion from Speed per Second to per Minute and per Hour

• Speed per Second → per Minute

  • 1 minute is 60 seconds → 5cm per second equals 300cm per minute.
  • Understanding changes in length helps understand changes in speed.

• Speed per Second → per Hour

  • 1 hour is 60 minutes → 300cm per minute multiplied further by 60.
  • Example: 300cm becomes 18000cm → 18000cm per hour.
  • Unit conversion: 1 meter = 100 centimeters → 180 meters.

Unit Conversion

• Conversion from Speed per Hour to per Minute and per Second
  • From per hour to per minute: Divide by 60.
  • From per hour to per second: Divide by 3600.

Summary

• Summary of Speed
  • Speed involves moving a certain distance in a certain time.
  • Speed is a combination of time and distance.
  • Thinking of speed as length makes calculations of speed per second, per minute, and per hour easier.