Two cars move in the same direction at 30 km h⁻¹ and are 5 km apart. A third car moving in the opposite direction meets them at an interval of 4 min. Find the speed of the third car.
Options

Question

Two cars move in the same direction at 30 km h⁻¹ and are 5 km apart. A third car moving in the opposite direction meets them at an interval of 4 min. Find the speed of the third car.

G1 Physics · Accepted Answer

Relative speed of third car with either car is v+30. Four minutes=1/15 h. Thus 5=(v+30)(1/15), giving v=45 km h⁻¹. Option D.