Why do you thin jack insists on going up to the mountain to look for the beast even though it's already dark when they arrive? What internal conflict does ralph feel about the decision to go up the mountain in the dark?

Pure and simple, Jack wants the pleasure of calling Ralph a coward. Jack is afraid, but he truly believes he's calling Ralph's bluff. Ralphis conflicted because he is leaving Piggy alone with the young boys and because it's too dark to do anything anyway. None-the-less, he is ready and willing to take the challenge..... scared or not.