A passenger train 100 m long is moving with a uniform velocity 45kmph. The time taken to cross a stationary goods train of length 1 km is

Length of the passenger train (s₁)=100m

Length of the goods train (s₂)=1km=1000m

Distance travelled by passenger train S=S₁+S₂=100+1000=1100m

Velocity of the train v = 45 kmph$\text{=45×}\frac{5}{18}12.5\text{m/s}$

Time taken$\left(\text{t}\right)=\frac{\text{s}}{\text{v}}=\frac{1100}{12.5}=88\text{s}$