Emma is a student in Melbourne and decides to host a house party. During the party, one of the guests, Nayar slips on a wet floor in the hallway and sustains a serious back injury resulting in immediate hospitalization. It is discovered by insurance investigators that Emma was aware of the wet floor but failed to warn her guests or take any measures to address the hazard at her house. 

Based on this premise briefly discuss the principles of duty of care and negligence in Australian tort law.