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

AI Thread Summary
To calculate the drag force on a missile with a diameter of 48 cm cruising at 270 m/s at low altitude, the drag force formula Fd = -1/2p(v^2)CA is used, where p is air density, v is velocity, and C is the drag coefficient. The user mistakenly used the diameter instead of the cross-sectional area in their calculations. The correct approach involves approximating the missile as a cylinder and calculating the cross-sectional area using the formula A = π(d/2)^2. After correcting the area, the drag force can be accurately computed. Understanding the geometry of the missile is crucial for proper calculations.
djester555
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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?
 
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0.48 is the diameter, not the cross-sectional area of the missile.
 
how do i calculate cross-sectional area?
 
djester555 said:
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.
 
The question mentions diameter, so you're supposed to assume the missile is a cylinder.
 

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