Two trains are running in opposite directions in the same speed. The length of each train is 120 meter. If they cross each other in 12 seconds, the speed of each train (in km/hr) is

Answer: Option C

Explanation:

From the given question,
we will first calculate the speed of train relative to man,
=> ( 60 + 6 ) = 66 km/hr ( we added 6 because man is running opposite )
Convert it in metre/second
$$\begin{aligned} = 66 \times\frac{5}{18} \\ = \frac{55}{3} m/sec\\ \text{Time it will take to pass man }\\ = 110 \times \frac{3}{55} \\ = 6 \text{ seconds} \end{aligned}$$

Answer: Option C

Explanation:

First convert speed from km/hr to m/sec

So, Speed = 72*(5/18) = 20 m/sec
Time = 26 seconds

Let the length of the train be x meters.
We know, Distance = Speed*Time.
[you can remember this formula as remembering DUST = D*ST... Distance=Speed*Time]

x+250 = 20*26
=> x = 270 meters

So length of the goods train is 270 meter

Answer: Option A

Explanation:

As Trains are moving in same direction,
So, Relative Speed = 40-20 = 20 kmph
= 20*(5/18) = 50/9 m/sec

Length of Train= Speed * Time

$$\begin{aligned} Length = \frac{50}{9}*5 \\ = \frac{250}{9} \\ =27\frac{7}{9} \end{aligned}$$

Answer: Option D

Explanation:

First convert speed into m/sec

Speed = 144*(5/18) = 40 m/sec

Time = Distance/speed
= 100/40 = 2.5 seconds

Answer: Option D

Explanation:

Speed = Distance/time = 300/18 = 50/3 m/sec

Let the length of the platform be x meters
then
$$\begin{aligned} Distance = Speed*Time \\ x+300 = \frac{50}{3}*39 \\ =>3(x+300)= 1950 \\ => x = 350 \text{ meters} \end{aligned}$$