Question

Two cars are moving in same direction with speed of
45 km/hr. They are separated by a distance of
5 km. What is the speed of a third car moving in
opposite direction if it meets the two cars at an
interval of 4 minutes?​

Answer 1

Answer:

Let the speed of the car is u then relative speed of car with respect to car c is (u+30)

Distance is 5 kilometres

Time is 4minutes= 4÷ 60 hours

Speed= distance/ time

U+30= 5/4/60

U+30=5×60/4

On solving above equation we get

U+30 = 75 then u= 75 - 30= 45 km/h

Answer 2

Answer:

30 km / hr

Explanation:

Given :

Two cars are  moving in same direction with velocity 45 km / hr.

Let two cars be A and B & third be C .

So relative velocity of A w.r.t. B :

$\displaystyle{V_{AB}=45-45=0 \ km/hr}$

Distance ( s ) = 5 km

Time ( t ) = 4 min or 4 / 60 hr.

Now third car moving in opposite direction :

Relative velocity of C w.r.t. A OR B  [ Let say A or B be x ]

$\displaystyle{V_{CX}=x-(-45)=x+45\ km/hr}$

Speed = Distance / Time

x + 45 = 5 /  ( 4 / 60 )

x + 45 = 300 / 4

4 x + 180 = 300

4 x = 120

x = 30 km / hr.

Thus speed of third car moving in  opposite direction is 30 km / hr