Proportion of planetary-period to the distance-from-the-sun

[glassy]

1. =Homework Statement
Kepler's law of planetary motion says that the square of the period of a planet (T^2) is proportional to the cube of the distance of the planet from the Sun (r^3). Mars is about twice as far from the Sun as Venus. How does the period of Mars compare with the period of Venus?

Homework Equations

The Attempt at a Solution

Does this mean that the period of Mars is about twice as long as Venus'?
T^2=Kr^3
2T^2=K2r^3
?

 

[PeterO]

1. =Homework Statement
Kepler's law of planetary motion says that the square of the period of a planet (T^2) is proportional to the cube of the distance of the planet from the Sun (r^3). Mars is about twice as far from the Sun as Venus. How does the period of Mars compare with the period of Venus?

Homework Equations

The Attempt at a Solution

Does this mean that the period of Mars is about twice as long as Venus'?
T^2=Kr^3
2T^2=K2r^3
?

Short answer , No.

When you write 2T^2 did you mean 2 * T^2 or did you mean (2T)^2

Similarly, your K2r^3 : K * 2 * r^3 or K * (2r)^3 or (K * 2 * r)^3