Tweet
The gravity of a planet depends purely on its mass.
<Maths&Physics>
The acceleration a, at a radius r from the centre of a planet of mass m is given by a =(G*m) /(r^2) . The same equation yields the force per unit mass the planet exerts on another body. (The two are equivilant. Will explain why if asked.)
G is Newton's gravitational constant, and has a numerical value of 6.6742 * 10^-11 N·m^2/kg^2 in SI units. Source: http://physics.nist.gov/cuu/Constants/
(The symbol ^ is short-hand for "to the power of", so "r^2" is "r to the power of 2", or r squared.)
</Maths&Physics>
As the gravity of a planet depends purely on its mass, and the planet in question has a lower gravity than Earth, we can conclude that it's mass is less. We know it to be bigger in the sense of a larger volume. So, it's average denisty must be a lot less than Earth's, which ties in with the lack of metals.
<Maths&Physics>
The acceleration a, at a radius r from the centre of a planet of mass m is given by a =(G*m) /(r^2) . The same equation yields the force per unit mass the planet exerts on another body. (The two are equivilant. Will explain why if asked.)
G is Newton's gravitational constant, and has a numerical value of 6.6742 * 10^-11 N·m^2/kg^2 in SI units. Source: http://physics.nist.gov/cuu/Constants/
(The symbol ^ is short-hand for "to the power of", so "r^2" is "r to the power of 2", or r squared.)
</Maths&Physics>
As the gravity of a planet depends purely on its mass, and the planet in question has a lower gravity than Earth, we can conclude that it's mass is less. We know it to be bigger in the sense of a larger volume. So, it's average denisty must be a lot less than Earth's, which ties in with the lack of metals.
Comment