1. The problem statement, all variables and given/known data I was told that for loss of head at entrance , the degree of contaction depends on how thick the pipe walls is . i really don't know the meaning , can someone clarify ? the author also stated that the loss coefficients will vary , for very thin tubes , k is very high ? head loss = k (V^2) / 2g 2. Relevant equations 3. The attempt at a solution as we can see , the haed loss is affected by velocity of water , how can thickness of pipe affect the head loss?