A physical quantity, by definition, can be measured. The two measurable quantities that can be obtained from a velocity-time graph that depicts the relationship between the velocity (v) and time (T) of a particle.
1.the time derivative, or graphically, the slope of the velocity-time graph at any time depicts the acceleration of the particle at that time, since acceleration is the rate of change of velocity with time, vector a = d(vector v)/dt
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2. If one wishes to calculate the displacement of a particle between two time instants, the area under the v-t curve between vertical lines drawn at the two time instants would yield the displacement, since the definite integral of velocity between two time instants yields the displacement of the particle between those instants, for velocity vector is the time derivative of displacement, or vector v= d (position vector r)/dt