A probe is launched vertically upwards from the surface of the Earth and rises to a height of approximately 200 kilometres.
A student models the motion of the probe after its engines cut out by treating it as a particle moving freely under gravity, taking g=9.8g = 9.8g=9.8 m s−2^{-2}−2 throughout.
State the assumption the student is making about ggg.
Explain why this assumption is not appropriate for this problem, and state whether the student's model gives a maximum height that is too large or too small.
Suggest one refinement the student could make to the model.