Kinematics Question 330
Question: A 120 m long train is moving towards west with a speed of 10 m/s. A bird flying towards east with a speed of 5 m/s crosses the train. The time taken by the bird to cross the train will be [Manipal 2002]
Options:
A) 24 s
B) 4s
C) 8s
D) 12s
Show Answer
Answer:
Correct Answer: C
Solution:
length=120m
speed=10m/s
The relative velocity of train with respect to bird is =(10+5)m/s=15m/s
Since they are opposite to each other then addition will be occurred.
Hence, in a frame of Reference in which bird is at rest the train is moving with velocity =5m/s
The train is 120m long hence time taken for time to pass (from where bird is) end to end is
Speed=distance $\times$ time
time=$\frac{120}{15}$=8sec
BETA
