Two cars are moving in the same direction with a speed of 30 km h-1. They are separated from each other by 5 km. Third car moving in the opposite direction meats the two cars after an interval of 4 min. What is the speed of the third car?

Question

Two cars are moving in the same direction with a speed of 30 km h-1. They are separated from each other by 5 km. Third car moving in the opposite direction meats the two cars after an interval of 4 min. What is the speed of the third car? (A) 30 km h-1 (B) 35 km h-1 (C) 40 km h-1 (D) 45 km h-1

Tardigrade Admin · Accepted Answer

Let speed of the third car be upsilon km h-1 Then, relative speed of third car with respect to two cars = ( upsilon + 30 ) km h-1 Two cars are separated by 5 km and third car crosses them in 4 min. ∴ upsilon + 30 = (5×60/4) = 75 ⇒ upsilon = 75-30 = 45 km h-1

Q. Two cars are moving in the same direction with a speed of $30 km h^{- 1}$ . They are separated from each other by 5 km. Third car moving in the opposite direction meats the two cars after an interval of 4 min. What is the speed of the third car?

$30 km h^{- 1}$

$35 km h^{- 1}$

$40 km h^{- 1}$

$45 km h^{- 1}$

Let speed of the third car be $υ km h^{- 1}$
Then, relative speed of third car with respect to two cars
$= (υ + 30) km h^{- 1}$
Two cars are separated by 5 km and third car crosses them in 4 min.
$∴ υ + 30 = \frac{5 \times 60}{4} = 75 \Rightarrow υ = 75 - 30 = 45 km h^{- 1}$

Q. Two cars are moving in the same direction with a speed of 30kmh−1. They are separated from each other by 5 km. Third car moving in the opposite direction meats the two cars after an interval of 4 min. What is the speed of the third car?

30kmh−1

35kmh−1

40kmh−1

45kmh−1