Q1: For a long pipe, the head loss

ANS:C - at the entrance and outlet both are ignored

In fluid mechanics, when analyzing flow in long pipes, it's a common assumption that the head loss at the entrance and the exit of the pipe can be ignored. This assumption is often made for long pipelines where the length of the pipe is much greater than the diameter of the pipe. The reasoning behind ignoring the head loss at the entrance and the exit is that as the length of the pipe increases, the effects of the entrance and exit losses become negligible compared to the losses due to friction along the length of the pipe. Therefore, the correct statement is: At the entrance and outlet both are ignored. It's important to note that while this assumption is common and often valid for long pipelines, in certain situations or for specific applications, the entrance and exit losses might need to be considered. However, as a general rule, in long pipe flow analysis, these losses are typically ignored.