Problems on Trains Questions Answers Formulas, Tips and Tricks

• 1. Problem on trains Formulae and Important facts

  
  

  1. Conversion from km/hr to m/s
  

  $$\begin{aligned} x&km/hr = \left(x*\frac{5}{18}\right)m/sec \end{aligned}$$
  
  2. Conversion from m/s to km/hr
  $$\begin{aligned} x&m/sec = \left(x*\frac{18}{5}\right)km/h \end{aligned}$$
  
  3. Time taken by a train of length l metres to pass a pole or standing man or a signal post is equal to the time taken by the train to cover l metres.
  
  4. Time taken by a train of length l metres to pass a stationery object of length b metres is the time taken by the train to cover (l + b) metres.
  
  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 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
  $$\begin{aligned} \frac{(a+b)}{(u+v)} sec \end{aligned}$$
  Please note this is just formula of time which is distance upon speed.
  We are just adding two distances and two speeds
  
  8. 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 = $$\begin{aligned} \frac{(a+b)}{(u-v)} sec \end{aligned}$$
  Please note as trains are moving in the same directions so we used (u-v)
  
  9. 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:
  
  $$\begin{aligned} (A's&speed):(B's& speed) = (\sqrt{b}:\sqrt{a}) \end{aligned}$$

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Problems on Trains Questions Answers