Why does the work done by gravity in moving an object depend only on the vertical displacement near Earth’s surface?
Near Earth’s surface, gravity is approximately constant (F = mg), and the force acts vertically. Thus, work (W = F⋅Δh) depends only on vertical displacement (Δh), as horizontal motion is perpendicular to the force.
Ref: NCERT Class 11 Physics, Thermal Properties and Gravitation.