1. What is Pressure?

Definition: Pressure is the force applied perpendicular to the surface of an object per unit area over which that force is distributed.

Unit: The SI unit of pressure is the Pascal (Pa), which equals one Newton per square meter (N/m²).

2. Dimensional Formula of Pressure

The dimensional formula for pressure is:

Where:

• \( M \) — Mass (kilograms)
• \( L \) — Length (meters)
• \( T \) — Time (seconds)

Derivation:
Force = mass × acceleration → [M L T⁻²]
Area = [L²]
Pressure = Force/Area → [M L T⁻²]/[L²] = [M L⁻¹ T⁻²]

3. Common Pressure Units

• Pascal (Pa) = N/m²
• Bar = 100,000 Pa
• Atmosphere (atm) = 101,325 Pa
• Torr = 133.322 Pa
• PSI (pounds per square inch) = 6,894.76 Pa

4. Using the Calculator

Tips: Enter the force in Newtons (kg·m/s²) and area in square meters. The calculator will compute the pressure in Pascals.

5. Frequently Asked Questions (FAQ)

Q1: Why is the dimensional formula important?
A: It helps verify equations and convert between different unit systems in physics and engineering.

Q2: What does negative pressure mean?
A: Negative pressure typically means pressure lower than atmospheric pressure, not negative in absolute terms.

Q3: How does pressure relate to stress?
A: Pressure is a special case of normal stress that is uniformly applied and always compressive.

Q4: What's atmospheric pressure in Pascals?
A: Standard atmospheric pressure is 101,325 Pa (or 101.325 kPa).

Q5: Can pressure be expressed in base SI units?
A: Yes, 1 Pa = 1 kg/(m·s²) when expressed in base SI units.