Read Slow Displacement: Work Equals Potential-Energy Change
A slowly moved suspended mass is in near-static equilibrium at every point. The applied-force work becomes the increase in gravitational potential energy.
Quasistatic Work Against Gravity is the central idea in this question pattern. Identify the condition in the stem before applying the method below.
Start with the condition
Use geometry to find the final height change. At the final position, resolve tension and horizontal applied force separately if a force value is also requested.
Build the governing relation
The work depends on vertical rise, not directly on the horizontal displacement.
Finish with a physical check
Check the limiting case before selecting an option: remove the special feature in the diagram or make the relevant parameter very large or very small. The result should reduce to a familiar relation.
OlympIQ exam lens
- ✓State the physical condition before choosing a formula.
- ✓Keep direction, sign and constraint information explicit.
- ✓Test one limiting case before committing to an option.
Using F times horizontal distance with only the final force ignores that the applied force changes during the slow displacement.
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