This section explains the process of converting units when two conversion factors are needed, using the example of converting speed from kilometers per hour to meters per second.

Example: Converting 72 km/h to m/s requires:

1. Converting kilometers to meters $1000 m = 1 km$
2. Converting hours to seconds $1 h = 3600 s$
3. Final result: 20 m/s

Highlight: When dealing with compound units like speed, each unit must be converted separately using appropriate conversion factors.

Definition: Compound units are measurements that combine two or more different units, such as speed (distance/time) or density (mass/volume).

Vocabulary:

• Compound units: Units that combine two or more basic units
• Speed conversion: The process of changing velocity measurements from one unit to another

This section presents a detailed 12-step process for converting units using a single conversion factor. The methodology is clearly structured to ensure accurate unit conversions.

Definition: A conversion factor is a ratio between two equivalent measurements expressed in different units.

Example: Converting 1200 meters to kilometers follows these key steps:

1. Write initial value (1200 m)
2. Set up conversion factor $1 km/1000 m$
3. Cancel out common units
4. Perform calculation to get 1.2 km

Highlight: The proper placement of units in the numerator and denominator is crucial for successful conversion.

Vocabulary:

• Numerator: The top part of a fraction
• Denominator: The bottom part of a fraction
• Conversion factor: A fraction that equals 1 and shows the relationship between two units