Question

Two bodies $A$ and $B$ are travelling with constant velocities of $20\text{m/s}$ and $30\text{m/s}$ in the same positive direction. The relative velocity of $A$ with respect $B$ is

• A. $10\text{m/s}$
• B. $-10\text{m/s}$
• C. $30\text{m/s}$
• D. $50\text{m/s}$

Answer 1

The correct option is B $-10\text{m/s}$

Let $v_A$ and $v_B$ be the velocities of body A and B.
Relative velocity of A w.r.t B, $v_{AB}=v_A-v_B=20-30=-10\text{m/s}$