Drag Force

Home > Physics > Classical physics > Dynamics

Drag Force

Drag Force
\[F_d = \frac{1}{2}\rho v^2 C_d A\]

Variables

Fd = drag force (N)
rho = fluid density (kg/m³)
v = relative velocity (m/s)
Cd = drag coefficient
A = reference area (m²)

Description

What is this formula?

The drag force equation calculates the resistive force exerted by a fluid on an object moving through it. The force depends on fluid density, object speed, drag coefficient, and reference area.


When to use it

Use this formula when analyzing aerodynamics, vehicle resistance, aircraft performance, fluid flow, or moving objects in air or water.


Example

An object moves through air at 20 m/s with drag coefficient 0.8 and frontal area 0.5 m². Air density is 1.225 kg/m³.


Data:

rho = 1.225 kg/m³

v = 20 m/s

Cd = 0.8

A = 0.5 m²


Formula:

Fd = 0.5*rho*v²*Cd*A


Substitution:

Fd = 0.5*1.225*20²*0.8*0.5


Result:

Fd = 98 N


Applications

Aerodynamics, automotive engineering, aerospace engineering, hydrodynamics, sports engineering, and fluid mechanics.

Download the fCalc app to calculate this formula and thousands more:

Language

English | Spanish |