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Relative velocity: same and opposite directions

Free notes · JEE Main Physics

Formulas

tcross=L1+L2v1+v2t_{cross} = \frac{L_1 + L_2}{v_1 + v_2}

Trains crossing in opposite directions

Worked example

A body moves with v = 10 m/s for 3 s, then v = 5 m/s for 2 s in the same direction. Find the total distance.

  1. Distance = area under the v–t graph.
  2. 10×3 + 5×2 = 30 + 10 = 40 m.

Answer: 40