If we integrate the velocity vector with respect to time, do we get the displacement vector or the position vector?
What I mean is that, do we integrate the velocity vector to get the displacement vector + constant, or can we say that position = integral of velocity vector + position at $(t=0)?$
Integrating velocity over a time interval gives the particle's displacement across that period.
The indefinite integral of velocity with respect to time gives the particle's position function up to an additive constant.
Not exactly. The integral $\displaystyle\int_{t_1}^{t_2}\boldsymbol v\,\mathrm dt$ of the velocity vector over the interval $[t_1,t_2]$ is the displacement $\vec{P_1P_2},$ i.e., the position vector of ${P_2}$ minus the position vector of $P_1.$
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