Is there anyone who can give me an investigatory project that is related to physics plus very functional?

Question

For example...tin can crushers...you know...something to help the world using scientific technologies...oh byu the way...its a high school project so...i hope I'll get ideas that i am capable of producing in a level of mine.

Answer 1

I don't know if it will help the world...but why does projected light act differently than reflected light. I used to work in the theatre, and I found that you can make yellow light by projecting equal amounts of red and green light, and toning it with a little blue light, on the same surface. But when you mix, for example, red and green paint, you get brown, not yellow. Why?