Model 4 Train Vs Pole/Signal Post/Man Section-Wise Topic Notes With Detailed Explanation And Example Questions

Answer: (b)

Distance covered in 10 minutes at 20kmph

= distance covered in 8 minutes at (20 + x ) kmph

20 × $10/60 = 8/60 (20 + x)$

200 = 160 + 8x

8x = 40 ⇒ $x = 40/8$ = 5 kmph

Answer: (c)

Distance covered by train in crossing a telegraphic post

= length of train

Speed of train = $\text"Distance"/ \text"Time"$

= $(150/12)$ m./sec.

= $(150/12 × 18/5)$ kmph = 45 kmph

Answer: (a)

Distance covered by train

= Length of train

Speed of train = 60 kmph

= $({60 × 5}/18)$ m./sec.

= $(50/3)$ m./sec.

Required time = $\text"Distance"/ \text"Speed"$

= $(75/{50/3})$ seconds

= ${75 × 3}/50$ seconds = 4.5 seconds

Answer: (d)

Using Rule 1,

Speed of the train = 144 kmph

= $144 × 5/18$ = 40 m/s

When a train crosses a pole, it covers a distance equal to its own length.

The required time

= $100/40 = 5/2$ = 2.5 seconds.

Answer: (c)

Using Rule 1,

Speed of train = 90 kmph

= $({90 × 5}/18)$ metre/second

= 25 metre/second

If the length of the train be x then,

Speed of train

= $\text"Length of train"/ \text"Time taken in crossing the signal"$

25 = $x/10$ ⇒ x = 250 metre

Answer: (b)

In this situation, the train covers it length.

Required time = $100/{30 × 1000}$ hr.

= ${100 × 60 × 60}/{30 × 1000}$ = 12 seconds