What is the symbol for Displacement?

The story behind the answer

Δr is the standard symbol for displacement: the finite change in position, defined as r_final − r_initial. The capital Greek delta (Δ) signals a finite change, while r denotes the position vector, so together they mean “change in position.” In contrast, r alone is just position (not a change), dr denotes an infinitesimal change used in calculus, and Dp isn’t a standard symbol here (Δp usually represents change in momentum).

Memory tip: “Delta means change.” If Δt is change in time and Δx is change in x, then Δr is the vector change in position—direction and magnitude—from start to finish, not the total path length.