Q1: If there is no impervious boundary at the bottom of a hydraulic structure, stream lines tend to follow :

ANS:C - a semi-ellipse

A semi-ellipse refers to a shape that resembles half of an ellipse, which is a closed curve resembling a flattened circle. In the context of fluid flow around hydraulic structures, a semi-ellipse doesn't typically describe the flow pattern. Instead, the semi-circular pattern arises due to the balance of forces in the fluid flow, particularly when there are no impervious boundaries at the bottom of the structure. The flow tends to organize itself into a semi-circular pattern as it navigates around obstacles or structures, including hydraulic structures like weirs or spillways. Therefore, in the absence of impervious boundaries, the streamlines of the fluid tend to follow a semi-circular path rather than a semi-ellipse. Thank you for your patience and understanding.