Q1: Euler number is defined as the ratio of inertia force to __________ force.

ANS:A - pressure

Pressure is a fundamental concept in physics and fluid mechanics, representing the force exerted per unit area on a surface. It arises from the collisions of particles (atoms or molecules) within a substance with the walls of a container or another object. Here are some key points about pressure:

1. Definition: Pressure (P) is defined as the force (F) acting perpendicular to the surface of an object divided by the area (A) over which the force is distributed. Mathematically, it can be expressed as: P=AF​
2. Units: The SI unit of pressure is the pascal (Pa), which is equal to one newton per square meter (N/m²). Other common units of pressure include atmospheres (atm), millimeters of mercury (mmHg), pounds per square inch (psi), and bars (bar).
3. Types of Pressure:
   • Absolute Pressure: The pressure measured relative to a perfect vacuum, with no pressure exerted by the surrounding atmosphere.
   • Gauge Pressure: The pressure measured relative to atmospheric pressure. Gauge pressure readings are commonly used in devices like tire pressure gauges.
   • Differential Pressure: The pressure difference between two points in a fluid system. It is often used to measure flow rates or to monitor filter clogging.
4. Pressure in Fluids: In a fluid (liquid or gas), pressure is transmitted equally in all directions. This principle, known as Pascal's Law, explains why liquids and gases exert pressure on the walls of their containers and any objects submerged or immersed in them.
5. Applications:
   • Hydraulics: Pressure is essential in hydraulic systems, where it is used to transmit force and control motion through the manipulation of fluids.
   • Pneumatics: In pneumatic systems, pressure is used to store energy and control the movement of mechanical components using compressed air or gases.
   • Meteorology: Pressure is a critical parameter in weather forecasting, with changes in atmospheric pressure indicating the presence of high or low-pressure systems, which influence weather patterns.