Q1: When the whole fluid mass rotates either due to fluid pressure or gravity or rotation previously imparted, the motion is known as

ANS:A - free vortex

When the whole fluid mass rotates either due to fluid pressure, gravity, or rotation previously imparted, the motion is known as a "forced vortex." In a forced vortex, the rotation of the fluid is controlled or forced by external factors such as mechanical devices, gravitational forces, or applied pressure gradients. The fluid particles move in circular paths around a central axis, and the velocity of the particles increases as the distance from the axis increases. This velocity profile creates a characteristic spiral or whirlpool-like motion within the fluid. Forced vortices are common in various fluid systems and engineering applications, including centrifugal pumps, cyclones, and tornadoes. They are distinguished from free vortices, where the motion is primarily due to the natural behavior of the fluid itself without external influence. Therefore, the correct term for the described motion is a "forced vortex."