What is the Difference Between Thrust and Pressure

The key difference between thrust and pressure is that thrust is the product of pressure and area, whereas pressure is the force that acts on a unit area.

Thrust and pressure are physical properties of objects or systems, and these measurements are related to the area of the object or system. The term thrust can be defined as the force that is exerted by an object that is perpendicular to the surface. On the other hand, pressure is the force exerted by any object per unit area. Usually, the abbreviation of thrust and force is F, and for pressure, it is P.

1. Overview and Key Difference
2. What is Thrust
3. What is Pressure
4. Thrust vs Pressure in Tabular Form
5. Summary

What is Thrust?

Thrust is a type of reaction force and is the force applied on a surface in a direction that is perpendicular or normal to the surface. More precisely, when a system is expelling or accelerating its mass in one direction, this accelerated mass can cause a force that has an equal magnitude, and it is in the opposite direction to the system. This reaction force can be described quantitatively using Newton’s 3^rd law. The unit of measurement for thrust is newtons (N) in the SI unit system. It is similar to the unit of force because the thrust is a type of force.

A most common example for thrust is the fixed-wing aircraft which generate forward thrust upon pushing the air in the direction opposite to the flight. This happens in several ways, such as from spinning blades of a propeller, a rotating fan that pushes air out from the back of the jet engine, through the ejection of hot gases from a rocket engine, etc.

Figure 01: A Jet Engine Testing Center

Similarly, concerning a rocket, it is propelled forward by its thrust force which is equal in magnitude and opposite in direction to the time-rate of the momentum change (of the exhaust gas that accelerates due to the combustion in the combustion chamber at the rocket engine nozzle).

What is Pressure?

Pressure is the force applied perpendicular to a unit surface area. When concerning a fluid, pressure is the stress at a point within a fluid. The SI unit of measuring the pressure is Pascal (Pa). The pressure is denoted by the symbol “P”. However, there are several common units used to measure pressure. Ex: N/m2 (Newton per square meter), psi (the pound-force per square inch), atm (atmosphere), 1/760 of atm is named as one torr.

Figure 02: High Pressure Manometer

The equation for the calculation of pressure is as follows:

Pressure = Force/Area

Furthermore, there are different types of pressure which include fluid pressure, explosion pressure, negative pressure, vapor pressure, etc.

What is the Difference Between Thrust and Pressure?

Thrust and pressure are physical properties of objects or systems. Thrust is a type of reaction force. It is the force applied on a surface in a direction that is perpendicular or normal to the surface. Meanwhile, pressure is the force applied perpendicular to a unit surface area. So, the key difference between thrust and pressure is that thrust is the product of pressure and area, whereas pressure is the force that acts on a unit area.

The following chart lists the differences between thrust and pressure in tabular form.

Summary – Thrust vs Pressure

Thrust and pressure are physical properties of objects or systems. The key difference between thrust and pressure is that thrust is the product of pressure and area, whereas pressure is the force that acts on a unit area.

Reference:

1. “Pressure.” Encyclopædia Britannica.

Image Courtesy:

1. “Engine.f15.arp.750pix” By U.S. Air Force photo by Sue Sapp – (Public Domain) via Commons Wikimedia

2. “MAXIMATOR-High-Pressure-Manometer-01a” By Photo by CEphoto, Uwe Aranas or alternatively © CEphoto, Uwe Aranas (CC BY-SA 3.0) via Commons Wikimedia