To convert acceleration from G's to miles per hour (mph), we need to understand that 1 G is equal to the acceleration due to gravity, which is approximately 32.174 feet per second squared (ft/s²) or 22 mph per second.
Given that information, we can calculate the conversion as follows:
9 G's * 22 mph/s = 198 mph
Therefore, 9 G's is equivalent to approximately 198 miles per hour.