you need to agree a working pattern - but again, it depends on your level.
I work FT on a notional 35h per week - truth is - to deliver teaching, research and admin, and ensure that my group practices within health and safety confines related to our field, I put in probably double this. Partly because my job is my hobby (how sad, I am a data analyst at heart and could crunch whichever database came my way for entertainment) but also because the safety aspects freaks me out (being responsible for others etc).
Fair enough - anyone else - the same.
Some of my PT colleagues, on a 0.6FTE basis, do the same, except that they have a late start in the morning around 10.30 / 11am, and are meant to leave earlier on a Friday. Again, they go above and beyond, as everyone else, to deliver.
An then, I have other (senior) PT colleagues who just do the hours. Out of the contracted days and times, they do not work. They do not pick up pastoral work. They do not pick up emergency calls. They have (once) let a research staff stranded in a foreign country on field trip when they were their emergency link with our institution. They rely on us FTimers to "be there" to pick up the slack. And this pisses me off.
And finally, we have my clinical researcher, PT, who, in the middle of a busy clinic, stopped halfway through the patients we were seeing, because "her time was up" - and went home.
So I would suggest that you work out what is the expectation in your unit, and your responsibilities. From my colleague, the ones doing well in term of being an appreciated colleague and not being a pushover are the ones doing a late morning start - but they are fortunate to be in a post with a lot of flexibility in when they come in...