What is the drag force on a missile at low altitude?

[djester555]

Homework Statement

Missile Calculate the drag force on a missile 48 cm in diameter cruising with a speed of 270 m/s at low altitude, where the density of air is 1.2 kg/m3. Assume C = 0.75.

Homework Equations

Fd = -1/2p(v^2)CA

The Attempt at a Solution

-1/2(1.2)(270^2)(0.75(0.48) = -15746.4 what am i doing wrong?

 

[Fightfish]

0.48 is the diameter, not the cross-sectional area of the missile.

 

[djester555]

how do i calculate cross-sectional area?

 

[Fightfish]

how do i calculate cross-sectional area?

Err...
Well, the usage of the term 'diameter' and general impression of the appearance of the missile should clearly hint towards approximating it as a cylinder / having a round cross-section at least.

 

[ideasrule]

The question mentions diameter, so you're supposed to assume the missile is a cylinder.