Question

Q19) 1.0 marks
train crosses two tunnels 210 m and 480 m
long in 64 seconds and 78 seconds
respectively. What is the speed of the train?
​

Answer 1

Answer:

distance =speed×time

speed of train A =210÷64=3.28m/s

speed of train B=480÷78=6.15m/s

Answer 2

Answer:

Required speed of the train is 617.143 m/s.

Step-by-step explanation:

Let, length of the train be x m and speed of the train y m/s.

We know, Distance = Speed × Time

It is given that the train crosses 210 m tunnel in 64 seconds.

So,

$(210 + x) = y \times 64 \\ x - 64y + 210 = 0....(1)$

Again the train crosses 480 m tunnel in 78 seconds.

$(480 + x) = y \times 78 \\ x - 78y + 480 = 0.....(2)$

We are Subtracting equation (2) from (1) and get,

$x - 64y + 210 - (x - 78y + 480) = 0 \\ - 64y + 78y + 210 - 480 = 0 \\ 14y - 270 = 0 \\ y = \frac{270}{14} \\ y = 17.143$

From equation (1),

$x - 64 \times 17.143 + 480 = 0 \\ x - 1097.143 + 480 = 0 \\ x - 617.143 = 0 \\ x = 617.143$

Therefore speed of the train is 617.143 m/s and length of the train is 17.143 m.

This is a problem of Speed and Distance chapter,

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