The utilitarian framework of ethics provides an answer in this specific case, if you make an assumption about the level of suffering the people will endure while being run over by the train. If the suffering of the one man when he gets hit by the train is equal to the suffering to any one of the five men when they get hit by the train, then is makes no difference that the one man will not die. Utilitarianism states that the greatest good is human pleasure, and the greatest bad is human suffering. In this case, the one man being immortal increases his capacity to suffer, while the five men can only experience the suffering once. This means that the one man will experience human suffering equal to the five men after five cycles of the tram, which will take 50 seconds. If I wasn't sure that I could break the chain and free the one man within 50 seconds, then the correct course of action is to let the five men die because human suffering will be greater overall for this system after 50 seconds, at the cost of one unit every ten seconds. If the one man could be sedated and experience no pain until the chains could be cut, then we are effectively performing a kind of surgery on the one man, and long periods of sedation would be justified while his chains are being cut.