relative velocity in 1d

Question

Car A moves east at 20 m/s. Car B moves west at 15 m/s along the same straight road. What is the velocity of B relative to A?

RankGuru · Accepted Answer

1. **Sign Convention**: Let East be the positive direction ($\hat{i}$).
2. **Define Velocities**:
   - $v_A = +20$ m/s ($20$ m/s East)
   - $v_B = -15$ m/s ($15$ m/s West)
3. **Relative Velocity Formula**: $v_{BA} = v_B - v_A$.
4. **Substitution**: $v_{BA} = (-15) - (+20) = -35$ m/s.
5. **Interpretation**: The negative sign indicates the direction is West.
6. **Final Result**: The velocity of B relative to A is **$35$ m/s West**.

Rank Guru

relative velocity in 1d

Select the correct option: