NTA Abhyas JEE Main2020PhysicsMotion in Two DimensionsPractice
Two trains are moving in the same direction along parallel tracks. One of them is 200 m long travelling with a velocity of 20 m s - 1 . The second one is 800 m long travelling with a velocity of 7 . 5 m s - 1 . The time taken for the first train to overtake the second is
Options
- A20   s
- B40   s
- C60   s
- D80 s
Correct answer
D. 80 s
Step-by-step solution
From the figure, the relative displacement is s r e l = 800 + 200 m = 1000 m υ r e l = υ 1 - υ 2 = 20 - 7.5 m s - 1 = 12.5 m s - 1 ∴ t = s r e l υ r e l = 1000 12.5 = 80 s