what 3 forces are acting on hamlet in the first act?

I would think melancholy, anger and revenge. By the end of Act 1, Hamlet has listened to his father ghost and resolves to think of nothing but revenge.

Here is a great quote at the end of act 1 where Hamlet pledges to wipe away all other parts of his life and think only upon vengence against his uncle,

"I'll wipe away all trivial fond records,

All saws of books, all forms, all pressures past,

That youth and observation copied there;

And thy commandment all alone shall live..."