1. The problem statement, all variables and given/known data It was established that the gravitational field strength at a height of 2.8*10^6m above the surface of Triton is 0.79N/kg. If a spacecraft was orbiting Triton at a height of 2.8*10^6m above the surface with a constant speed, what would be the reading on a spring balance in the spacecraft if a mass of 10kg was placed on the end of it? 3. The attempt at a solution I think it is 0N because a spring balance cannot weigh mass when in orbit. This is because everything in orbit is perpetually in freefall and moving at a constant speed. Everything on that space ship is weightless. There is always a gravitational field felt by every object in the spacecraft but the objects are perpetually falling in this field but without changing its distance from Triton because it is moving in a circle so the magnitude of this field is constant as well. There is no acceleration in any reference frame for every object in the spacecraft. In other words, no object experiences a reaction force even though every object experiences a force towards Triton. So no tension exists in the spring balance because every object accelerates in the same direction and with the same magnitude. This is the reason why no weight can be measured. Is my analysis correct? The answers just evaluated assuming the spring balance worked and got 7.9N.