If I had 2 bodies floating in space. Body 1 of Mass 10Kg and body 2 of mass 5Kg and then mass 1 exerted a force of 100N on body 2 both, assuming newtons 3rd law, should begin to accelerate away from one another.

Using F = Ma then making a (acceleration) the subject of the equation we find that body 1 takes on an acceleration of 10m/s/s. Meanwhile in the other direction body 2 has an a of 20m/s/s.

So far so good, a smaller mass suffers greater displacement under the same force...

When I worked out the work done on each object in joules it seemed counter intuitive. J = Fd or work = force x distance. In this case the distance is either 10m in the first second or 20.

Thusly for body 1. the work done = 100 x 10 or 1000J

for body 2 the work done is 100 x 20 or 2000J

In other words twice as much work has been done using the same force simply by moving a smaller object. Why doesnt the formula take into account the mass of the object being moved? I know this cant be right but ive looked up the formula and it seems set in stone.