Can my brother go to jail for beating up my little sister?

he is 16 and im 13 and my little sis is 8. he is really immature, today he tackled her and made her cry. then later on he punched her in back 3 times hard. He likes hitting her all the time. When ever I yell at him for it, he'll tell me to shut up or he will hit me next. I told him he could go to jail for that because shes too little and he said he can't and his loser friends took his side. Who is right here? me or him? He is so much bigger her and me and it's not fair to tackle her and punch her.