Question

5km
v= 30kmh)
v=30kmh
Two cars are moving with same velocity of 30 km h-1
maintaining a distance of 5 km between them. Speed
of third car moving in the opposite direction and
meeting the two cars at an interval of 240 s is:
(A) 45 km h-1
(B) 30 km h-1
(C) 55 km h-1
(D) 35 km h-1
​

Answer 1

t = 240s =240/60 = 4min/60 = 1/15 hr

dist = 5 km

speed of third car = 5/(1/15) = 75 kmph

thia speed will considered if the other two cars were in rest

. now as the other cars are also moving with 30kmph in opposite direction ,

its speed will.be taken as 75 - 30 = 45kmph.