Pressure and Fluids
A complete physics website covering pressure, fluids, atmospheric pressure, Pascal’s law, buoyancy, Archimedes’ principle, fluid pressure, density, Bernoulli’s principle, diagrams, formulas, flowcharts, solved examples, and exercises.
1. Pressure
Pressure is defined as the force acting per unit area.
Pressure = Force / Area
P = F / A
Force Applied
→
Acts on Area
→
Pressure Produced
2. Fluids
Substances that can flow are called fluids. Liquids and gases are fluids.
Characteristics of Fluids
- They can flow easily.
- They take shape of container.
- They exert pressure in all directions.
Density = Mass / Volume
ρ = m / V
3. Atmospheric Pressure
The pressure exerted by air surrounding Earth is called atmospheric pressure.
Normal atmospheric pressure = 1.013 × 10⁵ Pa
4. Pascal’s Law
Pressure applied to an enclosed fluid is transmitted equally in all directions.
Applications
- Hydraulic lift
- Hydraulic brakes
- Hydraulic press
5. Archimedes’ Principle
A body immersed in a fluid experiences an upward buoyant force equal to the weight of displaced fluid.
6. Bernoulli’s Principle
As velocity of fluid increases, pressure decreases.
Applications
- Airplane wings
- Perfume spray
- Carburetor
7. Applications of Pressure and Fluids
| Application | Principle Used |
|---|---|
| Hydraulic Lift | Pascal’s Law |
| Ship Floating | Archimedes Principle |
| Airplane Flight | Bernoulli Principle |
8. Practice Exercises
Short Questions
- Define pressure.
- What are fluids?
- State Pascal’s law.
- Define buoyancy.
- State Bernoulli’s principle.
Numerical Problems
- Find pressure if force is 200 N and area is 10 m².
- Calculate density of body of mass 20 kg and volume 5 m³.
- Find pressure if force is 500 N acting on area 25 m².
9. Formula Summary
| Topic | Formula |
|---|---|
| Pressure | P = F/A |
| Density | ρ = m/V |
| Fluid Pressure | P = hρg |