Hey could someone help me solve this question?

Two trains travelling at speeds of 36 kmph and 54 kmph cross each other in 8 seconds when travellling in opposite directions. Had they been travelling in same direction, in how much time would the faster train have crossed the slower train?

First convert 36 and 54 into m/s by multiplying by 5/18
U get 10m/s and 15m/s. Now as speed equals distance/time u have total speed when traveling in same direction as 15+10 and time as 8 u get distance 8*25 equals 200.
This is the length of the two trains now in the same direction the speeds will be subtracted 15-10 i.e. 5 m/s relative speed so 200/5 equals 40 secs this is your answer hope this helps

Speed of first train = 36 km/h = 10 m/s

Speed of second train = 54 km/h = 15 m/s

Time to cross in opposite directions = 8 seconds
Relative speed (opposite directions):
10
+
15
=
25
 
m/s
10+15=25m/s

Total length of both trains:
25
×
8
=
200
 
m
25×8=200m

Relative speed (same direction):
15
−
10
=
5
 
m/s
15−10=5m/s

Time to cross in same direction:
200
5
=
40
 
seconds
5
200
​

=40seconds