Final answer:
The use of an SI conversion tool for SI to English units is not practical due to the inconsistent conversion ratios inherent to the English system, unlike the decimal-based conversions of the metric system.
Step-by-step explanation:
The difficulty in using an SI conversion tool to convert from SI units to English units arises because the two systems are based on different fundamental principles. SI units, which form part of the metric system, are universally based on multiples of 10, making conversions straightforward and universally consistent. In contrast, English units are part of a system with varied conversion relationships that are not as systematically related.
For example, in the SI system, distances might be measured in meters, with 1,000 meters equaling a kilometer. Conversely, in the English system, 12 inches equal 1 foot, 3 feet equal 1 yard, and 5,280 feet equal 1 mile. Due to these inconsistent conversion ratios, a direct and singular tool for conversion like those used within the SI system is impractical for conversions between the two systems. Instead, a specific conversion factor must be employed for each SI to English unit conversion.