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Check my arithmetic for this formula. |
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| Mar9-09, 08:25 AM | #1 |
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Check my arithmetic for this formula.
I have this formula: F = qVe + (Pe - Pa) * Ae; I want to get q by its self. This what I did to get q by its self.
F = qVe + (Pe - Pa) * Ae [tex]\frac{F - (P_e - P_a)}{(A_e)} = \frac{(V_e * q)(A_e)}{(A_e)}[/tex] [( F - (Pe - Pa)) ÷ Ae] ÷ Ve = q This is how I got q by its self in order to solve for q. I'm not sure if its correct, so please look over it to see if its correct. Thank you for your time. |
| Mar9-09, 08:56 AM | #2 |
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It's wrong. When you move the (Pe-Pa)Ae term over to the side with F, you lost the Ae and multiplied Veq by Ae instead.
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| Mar9-09, 06:20 PM | #3 |
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| Mar9-09, 06:33 PM | #4 |
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Recognitions:
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Check my arithmetic for this formula.
I think what you did, correct me if I'm wrong, is subtract (Pe-Pa) from both sides and then divide everything by Ae.
The problem with this is that subtracting from the right hand side doesn't eliminate the (Pe-Pa) because it has an Ae attached to it. What Office_Shredder is saying is you have to move the entire term, Ae(Pe-P), over to the other side: [tex]F=qV_{e}+(P_{e}-P_{a})A_{e}[/tex] Subtract [tex](P_{e}-P_{a})A_{e}[/tex] from both sides: [tex]F-(P_{e}-P_{a})A_{e}=qV_{e}+(P_{e}-P_{a})A_{e}-(P_{e}-P_{a})A_{e}[/tex] [tex]F-(P_{e}-P_{a})A_{e}=qV_{e}[/tex] [tex]\frac{F-(P_{e}-P_{a})A_{e}}{V_{e}}=q[/tex] To make explicit what you did: [tex]F=qV_{e}+(P_{e}-P_{a})A_{e}[/tex] [tex]F-(P_{e}-P_{a})=qV_{e}+(P_{e}-P_{a})A_{e}-(P_{e}-P_{a})[/tex] And you see the terms don't drop out on the right hand side. Hope this clarifies. |
| Mar9-09, 09:06 PM | #5 |
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Ok, yes it does clarify. Ae is meant to multiply with (Pe - Pa) not to divide F - (Pe - Pa), which is not dividing but multiplying. Thank you for your help.
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