Amy and Josh are coasting on their bicycles down a 10° slope at 15 m/s through s

Question

Amy and Josh are coasting on their bicycles down a 10° slope at 15 m/s through still air. The mass of Amy and her bicycle is 60 kg. The mass of Josh and his bicycle is 90 kg. The cross-sectional area of Amy and her bicycle is 0.45, while the cross-sectional area of Josh and his bicycle is 0.60. The drag coefficient for both cyclists is 0.70. Other than gravity and air resistance, the external forces acting on the two bicycle and rider systems are the same. Which cyclist is more affected by air resistance? Please show work.

Explanation / Answer

Drag Force (Fd) = (Cd A v^2) /2
Where ,
Cd is Coefficient of Drag.
is air density = 1.226Kg/m^3 (At sea Level)
A is Cross Sectional Area
v is Relative Velocity

For Amy -
(Fd) = (0.7 * 1.226 * 0.45 * 15^2) /2

For Josh -
(Fd) = (0.7 * 1.226 * 0.60 * 15^2) /2

We can clearly see Fd for Josh > Fd for Amy. Therefore Josh is more affected by Air resistance.

Related Questions

Navigate

• Browse (All)
• Browse A
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.