Choose all of the examples of balanced forces.

A chandelier has been hanging in the kitchen for years
A log floats on top of the lake
You place your book on the top of a flat table
Your wagon rolls down the hill
The wind blows and turns the turbines of a windmill.

The drag force, fd, imposed by the surrounding air on a vehicle moving with velocity v is given by fd = cdaρv 2/2 where cd is a constant called the drag coefficient, a is the projected frontal area of the vehicle, and ρ is the air density. an automobile is moving at v = 80 kilometers per hour with cd = 0.28, a = 2.3 m2, and ρ = 1.2 kg/m3.