How long dose it take to get from Dublin to Cork by train?

I am planning on going to Cork soon just for a day trip would it be worth my while doing a day trip|||Hi There, I went to Cork from Dublin last year, I think the Train is about 3-4 hours driving is the Same both costing around 60-80 euros. I found the cheapest way to get there was to fly after days of browsing I got return flight for 29.00 euros