An object moves from one point to another. The change in gravitational potential energy $\Delta E_p$ of the object is given by $\Delta E_p = mg\Delta h$ where $m$ denotes the mass of the object, $\Delta h$ represents its change in height and $g$ is the acceleration of free fall. What condition must be satisfied for the equation above to be valid?
- AThe object must have a constant acceleration of $9.81\,\text{m s}^{-2}$.
- BThe object must be travelling in a uniform gravitational field.
- CThe object must be travelling only in a vertical direction.
- DThe resultant force on the object must be equal to its weight.