Understanding the Concept of Pressure in Physics: Definition, Formula, and Examples
By : romieduu
Understanding the Concept of Pressure in Physics: Definition, Formula, and Examples
Pressure is one of the important concepts in physics that is often encountered in everyday life. From air pressure, blood pressure, to pressure on objects under the surface of water, this concept helps us understand how forces act on a surface.
Definition of Pressure
In physics, pressure is defined as the force acting perpendicular to a surface per unit area. In other words, pressure describes how force is distributed over a certain area.
The pressure formula can be written as:
P=F/A
Where:
P = pressure (Pascal or N/m2)
F = force acting (Newton)
A = surface area (square meters)
Types of Pressure
Hydrostatic Pressure
This pressure occurs in liquids caused by the weight of the liquid above it. Hydrostatic pressure formula:
P=ρ⋅g⋅h
Where:
ρ\rho = density of liquid (kg/m3)
g = acceleration due to gravity (9.8 m/s2
h = depth of liquid (meters)
Air Pressure
Air pressure is the pressure produced by the weight of air in the atmosphere. This pressure is usually measured using a barometer and expressed in units of atmospheres (atm), millimeters of mercury (mmHg), or Pascals (Pa).
Absolute Pressure and Relative Pressure
Absolute pressure is the total pressure, including atmospheric pressure.
Relative pressure is the pressure calculated based on atmospheric pressure as a reference.
Factors Affecting Pressure
Force Amount
The greater the force acting on a surface, the greater the pressure.
Surface Area
The pressure will be smaller if the force is spread over a larger surface, and vice versa it will be greater if the surface area is smaller.
Depth (for fluid pressure)
At fluid, pressure will increase with increasing depth because the weight of the fluid above it also increases.
Example Questions and Discussions
Question 1:
A block weighs 500 N and is placed on a surface with an area of 0.5 m2. Calculate the pressure exerted by the block on the surface!
Solution:
Given:
F=500 N, A=0.5 m2
Use the formula:
P=F/A = 500/0.5 = 1000 N/m2
So, the pressure exerted is 1000 N/m2.
Question 2:
A submarine is at a depth of 50 m below sea level with a water density of ρ=1025 kg/m3. Calculate the hydrostatic pressure acting on the submarine!
Solution:
Given:
ρ=1025 kg/m3, g=9.8 m/s2, h=50 m
Use the formula:
P=ρ⋅g⋅h=1025⋅9.8⋅50=502250 Pa
So, the hydrostatic pressure that works is 502250 Pa or 502.25 kPa.
Application of Pressure in Daily Life
Air Pressure in Tires
The air pressure in vehicle tires affects driving comfort and safety. Tires with low pressure increase friction, while high pressure can reduce stability.
How Hydraulics Work
Tools such as hydraulic jacks use fluid pressure to lift heavy loads with less force.
Pressure in the Human Body
Blood pressure is an example of pressure that occurs in the human circulatory system. This pressure is important to ensure blood flows throughout the body.
Conclusion
Pressure is a fundamental concept in physics that plays a vital role in many aspects of our lives. Understanding pressure not only helps us solve problems in physics but also provides insight into various phenomena around us. By understanding the formula and principles of pressure, we can more easily understand its practical applications in the real world.