Mechanics
Drag Force
Resistive force on object moving through fluid.
Variables
FDN
Drag force
Air resistance force
In SI units: kg·m/s²
Allowed values: 0 or more
CDunitless
Drag coefficient
Shape-dependent constant
Allowed values: 0 or more
ρkg/m³
Fluid density
Density of fluid
Allowed values: greater than 0
Am²
Cross-sectional area
Projected area
Allowed values: greater than 0
vm/s
Velocity
Speed through fluid
Derivation
Derived from fluid dynamics and dimensional analysis.
Your notes
0/5000
Check value
Round inputs run through this page's calculator. Use it to test your own working or a rearranged form. It is a test case, not a real-world example.
- CD = 2 (Drag coefficient)
- ρ = 3 kg/m³ (Fluid density)
- A = 4 m² (Cross-sectional area)
- v = 5 m/s (Velocity)
Result: FD = 300 N
Other mechanics formulas with the same quantities
- Velocity (Kinematics) shares Velocity
- Kinetic Energy (Work & Energy) shares Velocity
- Power (Work & Energy) shares Velocity
- Momentum (Momentum) shares Velocity
- Rolling Kinetic Energy (Rotational Motion) shares Velocity
Where this formula is listed
- Mechanics formulas, under Dynamics, alongside Newton's Second Law, Weight, Friction Force, Hooke's Law and Center of Mass (Two Objects).
- In the mechanics list it comes after Hooke's Law and before Terminal Velocity.
- Mechanics formula sheet, one of 58 formulas printed with symbol keys and SI units.
- The full formula index, grouped by category and topic.
Common questions
What is the Drag Force formula?
Drag Force is written F_D = (1/2)C_D ρAv². Resistive force on object moving through fluid. It belongs to Mechanics, under Dynamics.
What are the units in F_D = (1/2)C_D ρAv²?
In SI units, F_D is drag force, measured in kg·m/s²; C_D is drag coefficient (dimensionless); ρ is fluid density, measured in kg/m³; A is cross-sectional area, measured in m²; v is velocity, measured in m/s.
How is the Drag Force formula derived?
Derived from fluid dynamics and dimensional analysis. The result is F_D = (1/2)C_D ρAv².