If a train of length 63 m having 7 freight cars rolls by you at the rate of three cars each second, what is the speed of the train?
(1) 6 m/s.
(2)7 m/s.
(3)21 m/s.
(4) 42 m/s.
Answers
Answer:
As we are give that total no. Of freight cars are 7. And length of Train is 63m.
Therefore length of each freight car is 9m.( No rocket science involved)
As 3 such cars pass in 1s.
Therefore total length covered relative to observer in 1sec is 9×3=27m.
Time taken to cover that distance is 1sec.
Now using relation between speed, distance and time. i.e. Speed=Distance/time.
27/1 meter per second
i.e. 27m/s.
Hope it Helps.
Explanation:
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The require answer is 21m/s.
speed : Speed is defined as
The rate of change of position of an object in any direction.
Speed is measured as the ratio of distance to the time in which the distance was covered. Speed is a scalar quantity as it has only direction and no magnitude.
As per the question we need to find speed of the train
The given is a train of length 63 m having 7 freight cars rolls by you at the rate of three cars each second
Length of the train-63m
Number of cars 7
Hence, length of 1 car - 63/7-9m.
Time taken for 3 cars-sec
Hence, time taken for 7 cars 7/3 sec
We know that Speed Distance Time-63/(7/3)-21m/s
Hence the require answer is 21m/s.
To learn more kinematics follow the given link
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