- #1

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If we write out the position vector in the vector notation and differentiate twice we get

**a**=-p

^{2}

**r**and this clearly is directed towards the centre of the axes system and not the focus.Any ideas?

- Thread starter aim1732
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- #1

- 430

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If we write out the position vector in the vector notation and differentiate twice we get

- #2

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Correct.If we write out the position vector in the vector notation and differentiate twice we geta=-p^{2}rand this clearly is directed towards the centre of the axes system and not the focus.

Ideas regarding what? I assume you are trying to prove Kepler's first law. The given equation does not describe a planet's motion. You need to find the right equation.Any ideas?

- #3

- 430

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I meant this.have to prove that it's acceleration vector passes through the focus of the conic----ellipse in this case as can be clearly seen.

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