# Keplers Constant Question

• quickslant
In summary, the conversation discusses the calculation of T, which represents the period in Kepler's third law. The units for T can differ, but the textbook suggests using seconds. The problem being solved is finding the average radius of Jupiter's orbital. The units for K are not specified, but they are likely to be m^3/seconds^2.

#### quickslant

I am given
K= 5.045 x 10^28
and T = 11.89 Earth years

I know that K = r^3/T^2

what i don't know is what should T be calculated in ? Earth years/earth days/ seconds? etc? can someone tell me what T shoudl be calculated in?

I think $$K = \frac{T^{2}}{r^{3}}$$

$$T$$ is the period in any unit.

in my textbook it says the other way around I am not sure though..
so it doesn't matter what units i use? won't i get a larger or smaller number depending on units?

quickslant said:
I am given
K= 5.045 x 10^28
and T = 11.89 Earth years

I know that K = r^3/T^2

what i don't know is what should T be calculated in ? Earth years/earth days/ seconds? etc? can someone tell me what T shoudl be calculated in?

You already have T in Earth years. That's as good a unit as any, unless of course you have been asked to do something with that information that you haven't bothered to write down. What is the problem you are trying to solve and what are the units of K?

K = m^3/T^2

Have a look at http://en.wikipedia.org/wiki/Kepler%27s_laws" [Broken]

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quickslant said:
K = m^3/T^2

You still have not told us the problem you are trying to solve, and you have not given the units specified for K. T is not a unit. I know what they probably are, but I could tell you that

K = 5.045 x 10^28 Parsecs³/century²

and from what you have told us so far, I might be right

sorry i was trying to calculate the average radius of jupiters orbital

i believe what htey wanted is m^3 / Days^2

vanesch said:
Have a look at http://en.wikipedia.org/wiki/Kepler%27s_laws" [Broken]

good lord i wish i never went to that site... way to many equations.. it look like graffiti for a second.. lol

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the textbook clearly mentions that T is to be calculated in seconds :)

Which textbook is that? Quickslant, go back to where ever you got that K= 5.045 x 10^28 figure. Surely, it gives the units also.

## What is Kepler's Constant?

Kepler's Constant, also known as the Astronomical Unit, is the average distance between the Earth and the Sun. It is approximately 149.6 million kilometers or 93 million miles.

## Who is Johannes Kepler?

Johannes Kepler was a German astronomer and mathematician who is best known for his three laws of planetary motion. He used the observations of Tycho Brahe to develop these laws.

## What is Kepler's Third Law?

Kepler's Third Law states that the square of the orbital period of a planet is directly proportional to the cube of the semi-major axis of its orbit. In simpler terms, it describes the relationship between a planet's distance from the Sun and the time it takes to orbit around it.

## How did Kepler discover his laws?

Kepler discovered his laws by analyzing the data collected by Tycho Brahe, a Danish astronomer. He used a combination of mathematics and observation to develop his laws of planetary motion.

## Why is Kepler's Constant important?

Kepler's Constant is important because it allows scientists to calculate the distances between planets and the Sun. It is also used in other astronomical calculations, such as determining the size and mass of planets and stars.