Hi! As is often the case with subtle nuances in vocabulary, their differences are not so clear-cut and the use of each one depends on context. Perhaps these links might help you, as they contain a lot of examples. http://www.wordreference.com/es/translation.asp?tranword=power http://www.wordreference.com/es/translation.asp?tranword=strength http://www.wordreference.com/es/translation.asp?tranword=force

Wow! How can such a simple question be so difficult to answer? These words have so many different meanings and uses depending on the context in which they are used. From your question, I can see you have encountered them in different contexts already. Sometimes the meaning is very precise: power and force have strict definitions in physics and engineering. At other times, they are seemingly interchangeable: a powerful man can be physically, mentally or politically strong; a force ten gale (wind) may be described as being very strong; and a forceful character can exert great power. None of these examples really answer your question or scratch the surface of the possible different meanings. I should say I'm new to this - it's my first attempt at answering a question - so I don't know whether this will be helpful. However, I'm tempted to say that yours is not the best question to ask. Maybe you should think about the different contexts in which you encounter these words and ask whether the other words make sense in the same context. For example, a bridge might be strong but it's unlikely to be forceful or powerful. It might be capable of resisting a powerful force but this isn't quite the same thing. If you asked me if a space rocket was powerful, I would say, "Yes," but if you suggested it was forceful that wouldn't make sense to me and I could tell you it was wrong. As I said, I don't know whether this will help or not. The fact that you are distinguishing different meanings of these three words must mean that your English is already at a good level. It's interesting to me that I can't explain the differences any better than this even though I know what the words mean. It shows me that the context in which words are used is so important. Defines the context and your question will make more sense.