Question

When riding a bicycle at steady speed, almost all of the energy expended goes into work you do fighting drag forces of air. As claimed in an earlier section of the text (see Equation 5.14), such drag forces are proportional to speed squared so...

a. The work done against drag forces decreases as speed increases.
b. The work done against drag forces increases linearly with speed.
c. The work done against drag forces increases with the square of speed.
d. The work done against drag forces remains constant regardless of speed.

Answer 1

The work done against drag forces on a bicycle increases with the square of the speed, as the drag force is proportional to the velocity squared.

Step-by-step explanation:

When riding a bicycle at steady speed and working against drag forces, which are proportional to the square of the speed, the correct statement is: c. The work done against drag forces increases with the square of speed. As the drag force, FD, is proportional to the velocity squared (v2), the faster the cyclist moves, the greater the drag force and thus, more work is needed to overcome this force. This is represented mathematically by the equation FD = CpAv2, where Cp is a coefficient related to the object’s drag, A is the frontal area, and v is the velocity.