# Gravity and Mass Question

1. Feb 21, 2008

This is just a general question on Gravity and Mass.

If you created a perfect sphere of a known element in the vacuum of space, which was 1 metre in diameter, i assume that it would exhibit a gravitational pull on other objects - although probably very weak.

If you then created another sphere exactly the same size, 1 metre in diameter, but with a known element that resulted in twice the total mass of the previous sphere, would it have twice the gravitiational pull as the previous sphere ?.

Thanks,

Regards,

Richard.

2. Feb 21, 2008

### lightarrow

Yes, if you compute the pull at the same distance from the sphere's centres.

3. Feb 21, 2008

### Lojzek

The mass must be equally distributed, so that sphere 2 has twice as high density
at all points.
(I assume that is what was meant by perfect sphere from a single element).

4. Feb 22, 2008

Thanks for the replies.

Not done the calculations, but essentially gravitational pull is directly proportional to mass, and is a linear relationship ?.

Regards,

Richard.

5. Feb 22, 2008

### Snazzy

The gravitational field strength at any point in space from the centre of an object is given as g = Gm / r^2 where r is the distance from the object's centre. So yes, gravitational field strength is directly proportional to mass.