Air resistance

Definition

Air resistance is the force exerted by air against the motion of a moving object. It acts in the opposite direction to the object's velocity, reducing its speed.

5 Must Know Facts For Your Next Test

1. It is often modeled as a function proportional to the velocity or the square of the velocity.
2. In differential equations, air resistance can be represented as $\text{F}_{d} = -bv$ for linear drag or $\text{F}_{d} = -bv^2$ for quadratic drag.
3. The corresponding differential equations are first-order and can be solved using methods for linear equations.
4. Air resistance affects terminal velocity, where the force of gravity is balanced by air resistance.
5. The inclusion of air resistance in modeling real-world systems leads to more accurate predictions of object behavior.

Review Questions

• What is the general form of a differential equation that includes linear air resistance?
• How does air resistance affect an object's terminal velocity?
• In what direction does air resistance act relative to an object's motion?

Related terms

Terminal Velocity: The constant speed that a freely falling object eventually reaches when the resistance of the medium prevents further acceleration.

First-order Linear Equation: A type of differential equation involving derivatives with respect to one variable and having no products or powers greater than one involving derivatives.

Drag Coefficient: A dimensionless number that quantifies an object's drag or resistance in a fluid environment such as air or water.