FORM 1-PHYSICS-PRESSURE

PRESSURE

Concept of Pressure

The Concept of Pressure

Explain the concept of pressure

Pressure is defined as the force per unit area. OR Pressure is the force acting normally (perpendicularly) per unit surface area.

It is calculated by the formula:

Pressure = Force (f)/Area (A)

P = F/A

Where

• P – Pressure
• F – Force
• A – Area

The S.I Unit of Pressure

State the S.I unit of pressure

The SI unit of Pressure is Newton per square metre (N/M²). This unit is usually referred to as the Pascal (Pa).

1Pa = 1 N/M²

The other units of pressure are atmosphere, torr bar and mmHg.

• 1 atmosphere = 780mmHg
• 1 atmosphere = 1 10⁵ N/M² = 1bar (used by meteorologists)

Note: for a given amount of force, the smaller the area of application the greater the pressure exerted.

When a man lifts a bucket of water by its handle that is made with a thin metal, he would experience some discomfort but if the bucket was made with a thicker handle the discomfort will be much less if any.

This is because the area over which the force is applied is larger.

Pressure due to Solids

Pressure in Liquids

Atmospheric Pressure