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A train 150 meters long is running at a speed of 54 km/hr. How much time will it take to cross a pole?
8 seconds
10 seconds
12 seconds
15 seconds
10 seconds
To convert km/hr to m/s, multiply by 185тАЛ. Since 54├Ч185тАЛ=15 m/s, the time taken is simply 15150тАЛ=10 seconds.
Length of train (distance to be covered) = 150 meters, Speed of train = 54 km/hr.
T=SDтАЛ
To convert km/hr to m/s, multiply by 185тАЛ. Since 54├Ч185тАЛ=15 m/s, the time taken is simply 15150тАЛ=10 seconds.
The most common error is failing to convert the speed from km/hr to m/s, leading to an incorrect result of 150/54тЙИ2.77 seconds.
Convert speed to SI units
Since the distance is in meters, convert the speed from km/hr to m/s by multiplying by 185тАЛ.
S=54├Ч185тАЛ=15┬аm/s
Apply time formula
To cross a stationary pole, the train must cover its own length. Using T=SDтАЛ:
T=15┬аm/s150┬аmтАЛ
Calculate final result
Perform the final division to find the time in seconds.
T=10┬аseconds
B is correct because the train covers 150 meters at 15 m/s, which results in 10 seconds.
This concept of covering one's own length is also used in calculating the time taken for a train to cross a bridge, where the total distance becomes Length┬аof┬аtrain+Length┬аof┬аbridge.