Calculate terminal velocity when given cross sectional area

AI Thread Summary
The discussion revolves around calculating the terminal velocity of a package with an opened parachute, given that the parachute increases the cross-sectional area by a factor of 31. The terminal speed of the first package, without a parachute, is 10 m/s. Participants clarify that the square of 10 m/s is 100 m²/s², which is crucial for the calculation. The relationship between terminal velocity and cross-sectional area is highlighted, emphasizing that terminal velocity is inversely proportional to the area. The final solution requires careful attention to units and calculations to arrive at the correct terminal speed for the second package.
Tatortotts
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Homework Statement


Two packages are dropped from an airplane. A parachute can increase the cross sectional area of each packages by a factor of 31. The parachute on package 1 fails to open, and the terminal speed of package 1 is 10 m/s. The parachute on package 2 opens.

What is the terminal speed of package 2 in m/s?

Homework Equations


Unsure, considering the problem gave very few numbers to work with.
R = ½CρAv2

The Attempt at a Solution


I figured since A (cross sectional area) is inversely proportional to vterminal2, that you would square package 1's vterminal (to get 100 m/s) and then divide by 31. I haven't submitted my answer yet so I'm not sure if it's right.
 
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Tatortotts said:
I figured since A (cross sectional area) is inversely proportional to vterminal2, that you would square package 1's vterminal (to get 100 m/s) and then divide by 31.
Have you left out a final step?
 
haruspex said:
Have you left out a final step?
Well, vterminal2 is proportional to 1/A, so 102 = 1/(A*31)
Solving for A I then get 1/3100 m/s, which seems a little ridiculous.
I submitted my answer (from my original solution--3.2 m/s) and it was wrong, so I know I'm missing something. I just can't seem to figure out what.
 
Tatortotts said:
Well, vterminal2 is proportional to 1/A, so 102 = 1/(A*31)
Solving for A I then get 1/3100 m/s, which seems a little ridiculous.
I submitted my answer (from my original solution--3.2 m/s) and it was wrong, so I know I'm missing something. I just can't seem to figure out what.
Here's a hint. The square of 10m/s is not 100m/s. What is it?
 
haruspex said:
Here's a hint. The square of 10m/s is not 100m/s. What is it?
Would it then be 100m2/s2? So I should take the square root of my answer?
 
Tatortotts said:
Would it then be 100m2/s2? So I should take the square root of my answer?
Yes.
 
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haruspex said:
Yes.
Thank you so much! I don't know why I decided to neglect units for that problem.
 
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