Following are the Important formulas to solve problems on trains…have a glance

**1**. km/hr to m/s conversion:

a km/hr = {a x 5/18} m/s.

**2**. m/s to km/hr conversion:

a m/s = {a x 18/5} km/hr.

**3.** Speed, Time and Distance:

Distance/Time, Time = Distance/Speed, Distance = (Speed x Time).

**3. **Time taken by a train of length L meters to pass a pole or standing man or a signal post is equal to the time taken by the train to cover L meters.

**4.**Time taken by a train of length L meters to pass a stationery object of length b meters is the time taken by the train to cover (L + b) meters.

**5.**Suppose two trains or two objects bodies are moving in the same direction at u m/s and v m/s, where u > v, then their relative speed is = (u – v) m/s.

**6.**Suppose two trains or two objects bodies are moving in opposite directions at u m/s and v m/s, then their relative speed is = (u + v) m/s.

**7.**If two trains of length a meters and b meters are moving in opposite directions at u m/s and v m/s, then the time taken by the trains to cross each other = (a + b) / (u+v) sec.

**9.**If two trains of length a meters and b meters are moving in the same direction at u m/s and v m/s, then time taken by the faster train to cross the slower train = (a + b) / (u – v) sec.

**10.**If two trains (or bodies) start at the same time from points A and B towards each other and after crossing they take a and b sec in reaching B and A respectively, then:

(A’s speed) : (B’s speed) = (√b : √a)

[WpProQuiz 9]