Recent content by matt_nz

Does this mean that in some sense the moon and Earth can be treated as one object that is spinning. If it was the case that there was no gravity (say both the Earth and moon where an empty shell 1mm thick), but there was a steel bar connecting the 2 of them, and the whole object was rotating...

I am still a bit unclear about this. The core of my question is more: "Why do I have to burn 1 million litres of fuel,to power the rockets that move the moon 1 degree off it's trajectory, but the Earth can do it for free." The rockets could not have an acceleration vector perpendicular...

I can see how that makes sense for me sitting in this chair, Gravity applies a force to me, but I do not gain kinetic energy and lose potential energy, as I am not moving. Therfore there is force, but not distance, so no energy. However my understanding of Newtonian physics is that something...

I have seen this topic discussed a bit on the web, but I don't see any clear answers. I takes a lot of energy to make the moon go in a curve, if you had to do it with rockets you would need a lot of fuel. Therefore it takes a lot of energy to make the moon go round the Earth for 4 billion...