Motion in Straight Line

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• Summary

This is the velocity of an object relative to some other object which might be stationary, moving slowly, moving with the same velocity, moving with higher velocity or moving in the opposite direction.

If initial position of two objects A and B are x_A (0) and x_B (0), the position at time t will be,

x_A (t) = x_A (0) + v_A t
x_B (t) = x_B (0) + v_B t

Displacement from object A to B, [ x_B (0) - x_A (0) ] + (v_B -v_A)t
Velocity of B relative to A = v_BA = v_B – v_A
Velocity of A relative to B = v_AB = v_A – v_B