Determine current using Kirchoff's Junction/Loop Rule

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The discussion focuses on applying Kirchhoff's Loop and Junction Rules to determine the currents i1, i2, and i3 in a circuit with specified resistances and voltages. The user initially sets up equations based on the rules but encounters difficulty with the last equation for I3. A suggestion is made to sum the previous equations to derive a solvable equation for I3. Ultimately, the user confirms they were able to solve the problem successfully. The application of Kirchhoff's rules is crucial for analyzing complex circuits effectively.
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Homework Statement



In the circuit shown in the figure, R1 = 6 Ω, R2 = 13 Ω, and R3 = 19 Ω, Vemf,1 = 10 V, and Vemf,2 = 15 V. Using Kirchhoff's Loop and Junction Rules, determine the currents i1, i2, and i3 flowing through R1, R2 and R3, respectively, in the direction indicated in the figure.



Homework Equations



i1 + 12 = 13

V=IR


The Attempt at a Solution



i1 + 12 = i3

V1 + I3R3 + I1R1 = 0

V2 + I2R2 + I3R3 = 0

I1 = (-V1 - I3R3)/R1

I2 = (-V2 - I3R3)/R2

I3 = (-V1 - I1R1)/R3

Does this look right?
 

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The last equation leads you nowhere. Instead, sum the two previous equations, that, together with the first equation, will give you an equation from which you will be able to find I3.
 
Thanks. I was able to solve it.
 
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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