How does an observer estimate the distance to an exploding round?

Estimating the distance to an exploding round relies on the time it takes for the sound of the explosion to reach the observer, and this method takes advantage of the properties of sound travel. The speed of sound in air at sea level under standard conditions is approximately 343 meters per second (or about 1,125 feet per second).

When the explosion occurs, there is a noticeable delay before the sound reaches the observer. By timing the interval between seeing the flash of the explosion and hearing the sound (the "bang"), the observer can calculate the distance using the speed of sound. The general formula to estimate distance is that the distance equals the speed of sound multiplied by the time (in seconds) it takes for the sound to arrive.

This calculation provides a relatively accurate estimate of how far away the explosion occurred, as long as conditions like temperature and humidity don’t significantly alter the speed of sound.

The other options mentioned involve methods that either do not provide a reliable estimate of distance in this situation or are less practical. For instance, timing the flash to bang with the speed of light is ineffective because the light from the explosion reaches the observer almost instantaneously, making it impossible to use this method for distance estimation. Measuring ground distance from the explosion is