Class 9 Physics: Fluid Pressure and Buoyancy

Fluid Pressure

• Fluid pressure is defined as the force exerted per unit area on an object immersed in a fluid (liquid or gas)
• Pressure increases with depth and depends on the density of the fluid
• Pressure is same in all directions at a given point in a fluid

Buoyant Force

• Buoyant force is the upward force exerted by a fluid (liquid or gas) on an object partially or fully immersed in it
• Buoyant force depends on the volume of the fluid displaced, density of the fluid, and acceleration due to gravity
• Buoyant force is responsible for objects floating or sinking in a fluid

Atmospheric Pressure

• Atmospheric pressure is the pressure exerted by the weight of air in the atmosphere on the surface of the Earth
• Atmospheric pressure decreases with altitude and increases with weather changes
• Atmospheric pressure is measured in units of pascals (Pa) or millibars (mbar)

Weather Forecasting

• Weather forecasting uses atmospheric pressure data to predict weather patterns and changes
• Low atmospheric pressure indicates bad weather, while high atmospheric pressure indicates good weather
• Changes in atmospheric pressure can indicate weather changes such as storms or fair weather

Archimedes' Principle

• Archimedes' Principle states that the buoyant force on an object is equal to the weight of the fluid displaced by the object
• The principle is used to calculate the buoyant force and density of an object in a fluid
• Archimedes' Principle has many practical applications in engineering, physics, and everyday life