# solving for two unknowns?

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• Jan 11th 2011, 03:17 PM
tommoturbo
solving for two unknowns?
Hello there need a bit of help in solving an equation to find two unknowns. the equation is

$P_o = \left( \frac{K_c y}{A x}\right)I_{in} + \frac{F_s z}{Ax}$

i need to find the values for x and y what i cant work out is how to isolate them and how to find 2 unknowns.

A= 5cm^2
Z= 75mm
x+y = 100mm
Kc= 2500 Newtons per Ampere
Po is in bar and is 0.2 at 4mA
Iin is in mA and is 4 at 0.2Bar
all units must be in SI

any help greatly appreciated. Thanks ian
• Jan 11th 2011, 03:24 PM
snowtea
x + y = 100mm
So y = 100mm - x

Substitue this for y.
Solve for x.
• Jan 11th 2011, 03:29 PM
rtblue
Are you given what $F_s$ is?

If so:

$x+y=100$
$x=100-y$

substitute this in for x, and solve for y.

If you're not given what $F_s$ is, then you actually have 3 unknowns, with 2 equations and you cannot solve for x or y.
• Jan 13th 2011, 01:57 AM
tommoturbo
thank you for the replies and help
i can see what i need to do
i have been transforming that equation all week but im obviously not doing it right i need to speak to my tutor im miising basic maths here

thanks again