Question 21: The time in which a train 180 m long, travelling at the speed of 30 kmph, will pass a signal pole is
[1] 21.6 min [2] 0.216 min [3] 21.6 sec [4] None of these

Answer:

Option: 3

Explanation:

Distance to be covered = 180 m.

Speed = 30 kmph. =>Time = 0.18/30 hrs = 21.6 sec.

Question 22: The time taken by a 90 m long train, running at the speed of 18 kmph to cross a bridge 270 m long, is
[1] 70 sec [2] 146 sec [3] 72 sec [4] None of these

Answer:

Option: 3

Explanation:

Distance to be covered = 90 + 270 = 360 m. Speed = 18 km/hr.

Time = 0.36/18 = 0.02 hrs = 0.02 x 60 x 60 sec = 72 sec.

Question 23: Find the time taken by two trains, one 180 m long and the other 270 m long, to cross each other, if they are running at speeds of 46 kmph and 54 kmph respectively. Consider both possible cases of motion.
[1] 202.5, 16.2 sec [2] 160, 100 sec [3] 108.45, 15.6 sec [4] 204.5, 14.8 sec

Answer:

Option: 1

Explanation:

Case I: Motion in same direction

=>Relative speed = 54 — 46 = 8 km/hr.

Distance to be covered = 180 + 270 = 450 m.

=>Time = 0.450/8 = 0.056 hrs = 202.5 sec.

Case II: Motion in opposite direction.

=> Relative Speed = 54 + 46=100 km/hr.

Distance to be covered = 180 + 270= 450 m.

=>Time = 0.450/100 = 0.00045 hrs = 16.2 sec.

Question 24: A person going from Pondicherry to Ootacamond travels 120 km by steamer, 450 km by rail and 60 km by horse transit. The journey occupies 13 hours 30 minutes, and the speed of the train is three times that of the horse-transit and \(1_2^1\) times that of the steamer. Find the speed of the train.
[1] 20 kmph [2] 60 kmph [3] 10 kmph [4] 50 kmph

Answer:

Option: 2

Explanation:

If speed of horse is X, then speed of steamer = 2X and

Question 25: A railway passenger counts the telegraph posts as he passes them. If they are 50 metres apart and the train is going at 48 kmph, how many posts will he pass per minute?
[1] 16 [2] 20 [3] 24 [4] 10