Q1: Mach number is defined as the ratio of the local flow velocity to the sonic velocity in the fluid. For what value of Mach number, the gases are considered incompressible ?

ANS:A - < 0.3

For gases, the Mach number (MaMaMa) is defined as the ratio of the local flow velocity (VVV) to the speed of sound (aaa) in the gas: Ma=VaMa = \frac{V}{a}Ma=aV​ Gases are typically considered incompressible when their Mach number is much less than 1. This is because at low Mach numbers, the density changes induced by the flow are negligible, and the gas can be treated as incompressible without significant error. Therefore, for gases to be considered incompressible, the Mach number (MaMaMa) should be: Ma<0.3Ma < 0.3Ma<0.3 This means that if the Mach number is less than approximately 0.3, the compressibility effects of the gas are minimal, and it can be reasonably approximated as incompressible for many practical engineering purposes. So, the correct answer is: < 0.3