Quote:
Originally Posted by ken0042
- Gravity. Keep in mind it's based on mass; not volume. I forget the exact numbers, but Jupiter is about 1000 times the volume of Earth. But the gravity is only about 10 times our own. So this planet having 1.5 times the volume may have as much or even less gravity. If their core is aluminum instead of iron like Earth's, it could have less mass. If you still have issues with my mass vs volume example; think of it this way- I'm going to throw a ball at your head and it's going to hit your head at 25 mph. Would you rather I throw a beachball, or a snooker ball? (One has more volume; one has more mass)
|
It's really based on both mass and volume. The farther you are away from the centre of the body (higher volume), the lower the gravity, and the more massive the object, the higher the gravity. And the quantity that relates these mass and volume is the reason for Jupiter's (relatively) weak gravity. This quantity is
density, equal to M/V.
Given density = p; G=constant of gravitation; R=radius:
g = 4πGpR/3