Relative Velocity

Step 1: Time taken by truck to reach pedestrian:
Step 2: Pedestrian must cross width in this time:
Step 3: Considering diagonal safe path:

Step 1: Initially rain appears vertical ⇒ horizontal component of rain = 8km/h.
Step 2: When speed becomes 12km/h: tan 30^∘ = (12 - 8)/(v) ⟹ v = 4√(3)
Step 3: Resultant speed: vᵣ = √(4√(3))² + 8² = 4√(7)km/h

Step 1: Time for truck to reach pedestrian: t = (4)/(8) = 0.5s
Step 2: Pedestrian must cross 2m in this time: v = (2)/(0.5) = 4m/s Considering diagonal safe path, vmin = 2.62m/s

Step 1: Understanding the Question:
The passenger in train A sees the entirety of train B pass by. We need to find the length of train B using the relative speed and time of observation.

Step 2: Key Formula or Approach:
1. For opposite directions, Relative Velocity .
2. Convert km/h to m/s by multiplying with .
3. Distance (Length of train B) = .

Step 3: Detailed Explanation:
Velocity of Train A, .
Velocity of Train B, .
Since they move in opposite directions, relative velocity of B with respect to A:
The passenger sees train B for 8 seconds. In this time, the entire length of train B passes the passenger.
Length of Train B = .

Step 4: Final Answer:
The length of train B is 320 m.