Q1: Pick up the correct statement from the following :

ANS:D - All the above.

All the above. Explanation:

1. In incompressible flow, the density of a fluid remains constant. In such flows, the fluid density does not change with variations in pressure and temperature. In practical terms, liquids like water are often considered incompressible for many engineering applications.
2. In compressible flow, the density of a fluid changes from point to point. Compressible flows involve fluids like gases where changes in pressure and temperature can significantly affect the density of the fluid. Therefore, the density of the fluid can vary at different points within the flow field.
3. In uniform flow, the velocity of a fluid does not change with respect to the length of the flow direction. In uniform flow, the velocity profile across any cross-section of the flow remains constant with respect to distance along the flow direction. This means that the flow remains steady and uniform over time and space.