Question

A train covers half of its journey with a speed of 30m/s and remaining half
journey with a speed of 20 m/s. Calculate the average speed of the train
during the whole journey.

Answer 1

Answer:

Let the total distance covered by the train is s.

We have to calculate the average speed of the train and average speed is given as

v_{avg} =\frac{s}{t}v

avg

=

t

s

Here, s is the the total distance and t is the total time taken.

Given speed for first half journey is 30 m /s and second half is 40 m/s.

Time taken for first half,

t_{1} =\frac{s/2}{30m/s}t

1

=

30m/s

s/2

and time taken for second half,

t_{2} =\frac{s/2}{40m/s}t

2

=

40m/s

s/2

Therefore average speed,

v_{avg} =\frac{s}{\frac{s}{60m/s}+\frac{s}{80m/s} }v

avg

=

60m/s

s

+

80m/s

s

s

v_{avg}=\frac{240}{7}v

avg

=

7

240

= 34.28 m/s.

Thus, the average speed of the train during the whole journey is 34.28 m/s.

#Learn More: speed

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