- #1

- 205

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so i take the derivative of the function which is (-1/R^2)dR/dt=(-1/R1^2)dR1/dt-(1/R2)dR2/dt

and then can calculate R to be 1/180 and i know R1, R2, and dR1/dt=.6 and

dR2/dt=.7

i get 5.052E-9 for dR/dt....which is not right

please help me

- Thread starter Rasine
- Start date

- #1

- 205

- 0

so i take the derivative of the function which is (-1/R^2)dR/dt=(-1/R1^2)dR1/dt-(1/R2)dR2/dt

and then can calculate R to be 1/180 and i know R1, R2, and dR1/dt=.6 and

dR2/dt=.7

i get 5.052E-9 for dR/dt....which is not right

please help me

- #2

Curious3141

Homework Helper

- 2,843

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Your derivative is correct (except for the typo where you left out the square on the R2 term). Check your algebra, and it should work out.

- #3

AlephZero

Science Advisor

Homework Helper

- 6,994

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1/80 + 1/100 does not equal 1/(80+100) = 1/180

.. and also the formula says

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