A runner completes a race in 9 m/s. How many kilometers per hour is this?

To convert the runner's speed from meters per second (m/s) to kilometers per hour (km/h), it's important to understand the relationship between these two units. One kilometer is equal to 1,000 meters, and one hour is equal to 3,600 seconds.

To perform the conversion, you start with the speed in meters per second and multiply by the number of seconds in an hour while dividing by the number of meters in a kilometer. The calculation can be expressed as follows:

1. Start with the speed: 9 m/s.

2. Convert it to kilometers per hour:

( 9 , \text{m/s} \times \frac{3600 , \text{s}}{1000 , \text{m}} ).

This simplifies to:

( 9 \times \frac{3600}{1000} = 9 \times 3.6 = 32.4 , \text{km/h} ).

Therefore, the correct conversion reveals that the runner's speed of 9 m/s is equivalent to 32.4 km/h. This understanding emphasizes the significance of familiarizing oneself with unit conversions, as they are foundational in mechanics and physics applications.