Pressure Calculator
Calculate pressure, force, or area using the pressure formula: P = F / A
Step-by-Step Solution:
1. Using the pressure formula: P = F / A
2. Substitute the values:
P = 500 N / 2 m²
3. Calculate:
P = 250 N/m² (pascals)
What is Pressure?
Pressure is the amount of force applied per unit area. It describes how a force is distributed over a surface. The same force creates much higher pressure when concentrated on a small area compared to a large area — this is why a sharp knife cuts but a dull one doesn't.
Pressure Formula:
P = F / A
where: - P = pressure (measured in pascals) - F = force applied (measured in newtons) - A = area over which the force acts (measured in m²)
This formula can be rearranged: - Force: F = P × A - Area: A = F / P
How to Calculate Pressure
To find pressure, follow these steps:
-
Determine the force: Measure or calculate the force being applied (in newtons or other units)
-
Measure the area: Determine the surface area over which the force is distributed
-
Divide force by area: Use the formula P = F / A
-
Include units: Express your answer in pascals, psi, or other pressure units
Example: A 500 N force is applied over an area of 2 m². - P = 500 N / 2 m² = 250 Pa
Understanding Pressure Units
| Unit | Symbol | Definition |
|---|---|---|
| Pascal | Pa | 1 N/m² (SI unit) |
| Kilopascal | kPa | 1,000 Pa |
| Atmosphere | atm | 101,325 Pa |
| Bar | bar | 100,000 Pa |
| PSI | psi | 1 lbf/in² ≈ 6,895 Pa |
| mmHg (Torr) | mmHg | ≈ 133.3 Pa |
Standard atmospheric pressure at sea level is approximately: - 101,325 Pa = 101.325 kPa = 1 atm = 1.01325 bar = 14.696 psi = 760 mmHg
Pressure in Fluids
In fluids (liquids and gases), pressure acts equally in all directions. The pressure at a depth in a fluid is:
P = P₀ + ρgh
where P₀ is the surface pressure, ρ is fluid density, g is gravity, and h is depth. This is why pressure increases as you dive deeper underwater.
Types of Pressure
Absolute Pressure: Measured relative to a perfect vacuum (zero pressure).
Gauge Pressure: Measured relative to atmospheric pressure. Most pressure gauges read gauge pressure (your tire pressure gauge shows 0 at atmospheric pressure).
Differential Pressure: The difference between two pressures, used in flow measurement and filtration.
Real-World Applications of Pressure
- Tire inflation: Maintaining proper tire pressure for safety and efficiency
- Weather forecasting: Barometric pressure changes indicate weather patterns
- Hydraulic systems: Brakes, jacks, and heavy machinery use fluid pressure
- Aviation: Cabin pressurization and altimeters rely on atmospheric pressure
- Medicine: Blood pressure measurement (systolic/diastolic in mmHg)
- Scuba diving: Understanding pressure changes at depth for safe diving
- Engineering: Designing pressure vessels, pipes, and structural supports
- Cooking: Pressure cookers use elevated pressure to raise boiling point
Common Questions About Pressure
What is the formula for pressure?
The pressure formula is P = F / A, where P is pressure, F is force, and A is the area over which the force is distributed. Pressure is measured in pascals (Pa) in SI units.
What is pressure in physics?
Pressure is the force applied per unit area. It describes how force is distributed over a surface. The same force creates higher pressure when applied to a smaller area, which is why a needle penetrates but a finger doesn't.
What are common units of pressure?
Common pressure units include pascals (Pa = N/m²), kilopascals (kPa), pounds per square inch (psi), atmospheres (atm), bar, and millimeters of mercury (mmHg). Standard atmospheric pressure is 101,325 Pa = 14.696 psi = 1 atm.
Why do snowshoes prevent you from sinking in snow?
Snowshoes distribute your weight (force) over a much larger area, reducing the pressure on the snow. Since P = F/A, increasing the area (A) while keeping force (F) the same results in lower pressure.
What is atmospheric pressure?
Atmospheric pressure is the force exerted by the weight of the atmosphere above a given point. At sea level, it averages about 101,325 Pa (14.7 psi). It decreases with altitude as there is less air above.