Question

please any one tell​

Answer 1

Question:-

A train passes 300 m long platform in 30s and it crosses a signal on the station in 12s. Find the speed of the train in km/h.

Solution:-

Let l and s be the length of train and speed of train respectively.

Now,

Length of platform = 300 m

∴ Time taken by the train to cross the signal,

$= \cfrac{\text{Length of train}}{\text{Speed of train}}$

$\Rightarrow \cfrac{l}{s} = 12$

$\Rightarrow l = 12s ... \left( 1 \right)$

Now,

∴ Time taken by the train to cross the platform,

$\Rightarrow 30 = \frac{l + 300}{s}$

$\Rightarrow 30s = 12s + 300 \quad \left( \text{From } \left( 1 \right) \right)$

$\Rightarrow 30s - 12s = 300$

$\Rightarrow s = \cfrac{300}{18} = \cfrac{50}{3} \; {m}/{s} = \cfrac{50}{3} \times \cfrac{18}{5} = 60 \; {km}/{hr}$

Hence the speed of the train is 60 km/h.