THEORY

In your high school physics classes, you learned all about various forces that act on matter. Ex:

​

• gravitational force
• electromagnetic force
• friction
• tension

​

Here I will introduce another force that is commonly overlooked. How many times have you been a trajectory problem with the comment "ignore air resistance"? Have you ever wondered what would happen if it is not ignored?​

 

 

Drag force is caused by the movement of an object through a medium. It is included in the F(net) calculation just like any other force. ​

​

Drag is given by the formula:

where:

F(D) = drag force (N)

ρ = density of the medium (kg/m^3)​

A = impact area of the object (m^2)

C(D) = coefficient of drag

v = velocity (m/s)

​

​

                                                     Some common drag coefficients are listed here:

​

​

Notice that the smallest drag coefficient is the 'streamlined' body. Where have you seen this shape before?

​

Some animals have evolved to be shaped similarly to the "streamlined body" because it is the most aerodynamic. This shape is also used in planes, submarines, and other transportation as a way to minimize the amount of energy needed to overcome drag.