Originally Posted By: paul
using two 1 kg masses

and accelerating them both at 40 m/s toward each other.

the result shows that neither mass has recieved double the momentum of the other mass.

because both 1 kg masses move away from each other at 40 m/s


The mass on the left changed it's momentum from 40kgm/s to -40kgm/s. That's a difference of -80kgm/s.

The mass on the right changed it's momentum from -40kgm/s to 40kgm/s. That's a difference of 80kgm/s.

A change in momentum of only 40kgm/s (1 times) would cause it to stop, not change direction.

This is the reason solar sails are supposed to be reflective, not black. Photons bouncing off give twice as much momentum as photons that are absorbed.