What is the Terminal Velocity of a Skydiver with Given Parameters?

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The discussion focuses on calculating the terminal velocity of a skydiver using the equation D = 1/2 C p A v^2 and the relationship bv = mg. The user attempts to solve for terminal velocity and arrives at a value of 1.38 m/s, but is questioned about the accuracy of this result. A key point raised is the potential oversight in converting the area from cm² to m², which could significantly affect the velocity calculation. The conversation emphasizes the importance of unit conversions in physics problems.
newbe318
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Homework Statement


I attached a screen shot of the problem.
Screen Shot 2015-10-14 at 9.40.16 PM.png


Homework Equations


D= 1/2 C p A v^2
bv=mg

The Attempt at a Solution


I spent 3 long hours on this problem. I confused myself even more. Please help me understand what is going on.
 
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Please show your best attempt with reasoning.
 
I know that at terminal velocity, bv=mg ... so, mg=1/2CpAv^2.. would I just solve for v? .. v=sqrt((2mg)/(CpA))... v=1.38m/s ?
m: 84kg
C: 0.8
p: 1.2kgm^3
A: 987cm^2
 
newbe318 said:
I know that at terminal velocity, bv=mg ... so, mg=1/2CpAv^2.. would I just solve for v? .. v=sqrt((2mg)/(CpA))... v=1.38m/s ?
m: 84kg
C: 0.8
p: 1.2kgm^3
A: 987cm^2
That's the right approach, but I don't understand how you get such a small velocity. Did you forget to convert the area to m2?
 
The book claims the answer is that all the magnitudes are the same because "the gravitational force on the penguin is the same". I'm having trouble understanding this. I thought the buoyant force was equal to the weight of the fluid displaced. Weight depends on mass which depends on density. Therefore, due to the differing densities the buoyant force will be different in each case? Is this incorrect?

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