Question

is the work positive or negative when a satellite is moving away from a planet?

Answer 1

Positive

Answer 2

Which system is the work being done on?

The satellite is doing positive work on the earth to escape orbit, but the earth does negative work on the satellite.

Answer 3

Wok is a scalar. We are only concerned with the magnitude.

Answer 4

Sure, but the sign of the work depends on how we draw our system boundary and which system we are analyzing.