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Physics · Ch 2 — Kinematics

Displacement Vector in Cartesian Coordinate System

2.7.1

Displacement Vector in Cartesian Coordinate System

Writing positions as position vectors turns 'displacement' into a single vector subtraction. If a particle moves from point P1P_1, with position vector r⃗1=x1i^+y1j^+z1k^\vec r_1 = x_1\hat i+y_1\hat j+z_1\hat k, to point P2P_2, with position vector r⃗2=x2i^+y2j^+z2k^\vec r_2 = x_2\hat i+y_2\hat j+z_2\hat k, then the displacement vector is

Δr⃗=r⃗2−r⃗1=(x2−x1)i^+(y2−y1)j^+(z2−z1)k^\Delta\vec r = \vec r_2 - \vec r_1 = (x_2-x_1)\hat i + (y_2-y_1)\hat j + (z_2-z_1)\hat k …

Figure 2.27Displacement vector

What this figure shows. A particle moving from point P1P_1 (position vector r⃗1\vec r_1) to point P2P_2 (position vector r⃗2\vec r_2); the displacement vector Δr⃗=r⃗2−r⃗1\Delta\vec r = \vec r_2 - \vec r_1 is drawn as the arrow directly from P1P_1 to …