Dave's ESL Cafe's Student Discussion Forums

[Chan-Seung Lee]

[redset]

"The iron acts to accelerate" means that the iron is responsible for the acceleration, its action causes the effect. You could say "acts in accelerating" but that implies that other things are involved in producing the acceleration, as though the iron isn't the only thing acting. We wouldn't say acts for in this way.

It's fairly common for native speakers to use this form when they're talking about taking action, usually to solve a problem or to make something important happen. It's quite formal though, the kind of thing you'd hear on news reports or in textbooks. You wouldn't really hear people using it in everyday speech.