# B Very large falling objects

1. May 14, 2018 at 1:38 AM

### Lucw

Hello

We stop the moon on its orbit around the earth.
Oups. The moon falls on the earth.
Or.
We bring jupiter at 400000 km from the earth.
And jupiter falls on the earth.

Are the fall times the same?

Have a nice monday

Lucw

Last edited by a moderator: May 14, 2018 at 6:46 AM
2. May 14, 2018 at 7:02 AM

### Staff: Mentor

No. Fall times will be the same only for objects whose mass is so small that the Earth can be considered as not being accelerated by the falling object. This will not be the case for Moon or Jupiter. In the latter case, it would rather be the Earth that would fall on Jupiter rather than the other way around!

3. May 14, 2018 at 8:00 PM

### Staff: Mentor

Hi Lucw. As mentioned by @DrClaude they are not the same. The more massive objects will accelerate more quickly toward each other because the attractive force is higher.

Based on this thread and your last one, it looks like it would help for you to learn more about the math behind the gravitational force between two massive bodies. Have you been able to learn some calculus yet, or is that coming up? There are a couple of previous PF threads that discuss the motion of two massive bodies in space that are pulled together by gravitational forces. In the general case, the math involves calculus, but it can be simplified to an Excel spreadsheet (with plots) if that would be more intuitive for you.