# FORM ONE PHYSICS STUDY NOTES TOPIC 7-9.

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35  TOPIC 7: 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.