Question 38

How long (time in seconds) will a 450 metre long train take to cross a girl walking with a speed of 5 km/hr in the direction of the moving train. The speed of the train is 65km/hr?

Solution

Length of train = 450 m

Speed of train = 65 km/hr and speed of girl = 5 km/hr

Since, they are moving in the same direction, relative speed = 65 - 5 = 60 km/hr

= $$60 \times \frac{5}{18} = \frac{50}{3}$$ m/s

Let time taken = $$t$$ sec

=> $$t = \frac{450}{\frac{50}{3}}$$

=> $$t = 450 \times \frac{3}{50}$$

=> $$t = 9 \times 3 = 27$$ sec

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