I have this problem here where I need to find V2 in 3 different cases and I have trouble of knowing how to take on the problem. Could someone please lead me into the right direction. I can't really find anything on how to go on this kind of problems. 

[![enter image description here](https://i.stack.imgur.com/FblxT.png)](https://i.stack.imgur.com/FblxT.png)