Two trains are travelling at the same speed in different directions. If each train is 120 metres long and crosses in 12 seconds, the speed of each train (in kilometres per hour) is:
A. 10
B. 18
C. 36
D. 72
Answer:C
Two trains are travelling at the same speed in different directions. If each train is 120 metres long and crosses in 12 seconds, the speed of each train (in kilometres per hour) is:
A. 10 B. 18 C. 36 D. 72
Explanation: Assume that each train travels at a speed of x m/sec.Then the two trains' relative speed equals 2x m/sec.As a result, 2x = (120 + 120/12) => 2x = 20 => x = 10.As a result, each train's speed is 10 m/sec, which equals ( 10 x 18/5) km/hr, or 36 km/hr.