An autonomous subterranean drilling probe is descending vertically down a deep shaft. To ensure a gentle halt at the bottom, its descent is slowed first by expanding mechanical braking pads that press against the shaft walls, and then, in the final few meters, by firing a downward-facing high-pressure gas thruster (which provides an upward force).
Describe the energy changes that occur, in terms of the work done by the forces acting on the probe, as it descends from the top of the shaft to a complete stop at the bottom.
57 exam-style questions on Edexcel GCSE Physics 8.1 Energy transfers and work. Each one has a worked solution and a mark scheme showing where the marks go.