two cars are moving in the same direction with speed 30 km/hr. they are separated by a distance of 5 km. what is the speed of a car moving in the opposite direction if it meets these two cars at an interval of 4 mins?
Answers
if the car moving in the opposite direction meets the car in 0th sec then it meets the car 5 km away from it in 4th sec. let the car moving in opposite direction is B in x km/m. we conclude that it reaches the first car at at the next 4 min it is going to meet A at point o.
30 km/h = 0.5 km m⁻¹··············→ ←··············x km m⁻¹
A ··························o·························· B
5 km in 4 min
let o be the point at which these cars meats each other
A ··························o·························· B
S₁ S₂
s₁ + s₂ = 5
v₁(t) + v₂(t) = 5
v₁ + v₂ = 5/4 = 1.25
0.5 + v₂ = 1.25
v₂ = 1.25 - 0.5 = 0.75 km m⁻¹ = 45 km h⁻¹