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A train 150 m long is running at the rate of 30 m/sec. What time will

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Bunuel
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A train 150 m long is running at the rate of 30 m/sec. What time will [#permalink] A train 150 m long is running at the rate of 30 m/sec. What time will   28 Apr 2021, 04:45
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A train 150 m long is running at the rate of 30 m/sec. What time will it take to cross a man walking in the opposite direction at the speed of 5 m/sec?

(A) 3 sec
(B) 4 2/7 sec
(C) 5 sec
(D) 6 sec
(E) 7 sec
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B
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B
aryamanpanda
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Re: A train 150 m long is running at the rate of 30 m/sec. What time will [#permalink] A train 150 m long is running at the rate of 30 m/sec. What time will   28 Apr 2021, 04:52
//train// ------------------------> 30m/s

5m/s <------------------------- //person//

the relative speed of the train would then be = speed of train + speed of man (opp direction)

Rel_speed = 35m/s
distance = 150 m

time taken = distance / rel_speed
= 150/35 = 30/7 m/s

hence B
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Re: A train 150 m long is running at the rate of 30 m/sec. What time will [#permalink] A train 150 m long is running at the rate of 30 m/sec. What time will   28 Apr 2021, 05:01
Given: A train 150 m long is running at the rate of 30 m/sec.
Asked: What time will it take to cross a man walking in the opposite direction at the speed of 5 m/sec?

Distance to be travelled = 150 m
Relative speed = 35 m/s
TIme required = 150 / 35 = 30/7 = 4 2/7 sec

IMO B
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B
ManyataM
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Re: A train 150 m long is running at the rate of 30 m/sec. What time will [#permalink] A train 150 m long is running at the rate of 30 m/sec. What time will   28 Apr 2021, 05:03
Bunuel wrote:
A train 150 m long is running at the rate of 30 m/sec. What time will it take to cross a man walking in the opposite direction at the speed of 5 m/sec?

(A) 3 sec
(B) 4 2/7 sec
(C) 5 sec
(D) 6 sec
(E) 7 sec


Time = distance /speed
time = 150/30+5
time 30/7 sec
which is 4 2/7 sec
answer is option B
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Re: A train 150 m long is running at the rate of 30 m/sec. What time will [#permalink] A train 150 m long is running at the rate of 30 m/sec. What time will   28 Apr 2021, 05:32
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Solution:

When two bodies move in SAME direction, Relative Speed is DIFFERENCE of the speeds of the bodies

When two bodies move in OPPOSITE direction, Relative Speed is SUM of the speeds of the bodies

Here,

Distance = 150m

Relative Speed = 30+5 = 35 m/sec (As the bodies are moving in opposite direction)

Time taken = Distance/Speed

= 150/35

=30/7 m/sec (option b)

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Re: A train 150 m long is running at the rate of 30 m/sec. What time will [#permalink] A train 150 m long is running at the rate of 30 m/sec. What time will   03 Dec 2023, 08:02
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Re: A train 150 m long is running at the rate of 30 m/sec. What time will [#permalink]
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