What is the equation used to measure distance using the flash-to-bang method?

• A. Time of Flight x 350 = Distance
• B. Elapsed Time between Impact and Sound x 350 = Distance
• C. Elapsed Time between Flash and Bang x 350 = Distance
• D. Elapsed Time between Impact and Sound x 350 = Distance

Answer: (B)

Measuring distance with the flash-to-bang method relies on how long sound takes to travel from the source to you. When you see the flash, that instantaneously marks the event, and the delay you hear the bang is the time sound needed to cover the distance to you. Using the speed of sound in air, about 350 meters per second, you convert that time interval directly into distance: distance equals the elapsed time between the flash and the bang multiplied by 350. This is why the correct option uses the elapsed time between the flash and the bang and multiplies by 350 to get distance.

The other options don’t fit because they pair the distance with the wrong time interval or the wrong starting event. Using “time of flight” or “elapsed time between impact and sound” doesn’t correspond to the moment you observe the event’s light and then hear it, which is essential to this method.