To convert 42 meters per 15 seconds into meters per second:

$\text{Speed} = \frac{42 \, \text{meters}}{15 \, \text{seconds}} = 2.8 \, \text{meters per second}.$

So, the speed is 2.8 meters per second.

Would you like more details or have any questions?

Here are some related questions:

1. How can I convert this speed to kilometers per hour?
2. What is the distance traveled in 30 seconds at this speed?
3. How would the speed change if the distance were 50 meters in 15 seconds?
4. How can I calculate average speed if the distance varies over time?
5. What is the formula to convert meters per second to miles per hour?

Tip: To convert meters per second to kilometers per hour, multiply by 3.6.