##### Problems on Trains

# Problems On Trains – Aptitude Tricks & Shortcuts & Formulas

**Important Formula :**

1.**To convert from km/****hr**** to m/sec **: **Multiply by ****5/18 ** m/s.

2.**To convert from m/sec to Km/****hr **: **Multiply by ****18/5** km/hr.

3. Formulas for finding Speed, Time and Distance

4. 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.

5. 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**.

6. 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**.

7. 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**.

8. If two trains of length a metres and b metres 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 metres and b metres are moving in the same direction at u m/s and v m/s, then:

The 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)**