# Orbital Periods

Just looking for a place to start, not all the work.

## Homework Statement

3 The asteroid belt between Mars and Jupiter consists of many fragments (which some
space scientists think came from a planet that once orbited the Sun but was destroyed).
(a) If the radius of the asteroid belt (where the orbit of the planet would have been) is
about three times larger than the distance between the Sun than the Earth, how long
would it have taken this hypothetical planet to orbit the Sun? (b) Can we use these data to
deduce the mass of this planet

## Homework Equations

T=1.4sqrt((a/r)^3) this is for Earth.
sqrt = square root

## The Attempt at a Solution

No idea where to start. I'm assuming we say it has the same density as Earth.

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SammyS
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## Homework Equations

T=TE sqrt((a/r)^3)...
"a" is the radius of the hypothetical planet.

Where does the 1.4 come from?