# Air Resistance

Written by Jerry Ratzlaff on . Posted in Classical Mechanics

Air resistance is a force that affects an object that moves through the air.

### Air Resistance formula

(Eq. 1)  $$\large{ F_a = -kv }$$   (This formula is for smaller objects at slower speeds.)

(Eq. 2)  $$\large{ F_a = - \frac{1}{2} k \rho A v^2 }$$   (This formula is for larger objects at higher speeds.)

Where:

$$\large{ F_a }$$ = force of air resistance or drag

$$\large{ \rho }$$  (Greek symbol rho) = atmosphere density

$$\large{ A }$$ = cross-section area of the object

$$\large{ k }$$ = air constant depends upon the shape of the object being dropped and the atmosphere density

$$\large{ v }$$ = velocity of the moving object