# Problems on Trains Quiz Set 012

### Question 1

A train of length 255m is running at a speed of 51m/s. How long will it take to cross a pole standing alongside the track?

A

5 sec.

B

6 sec.

C

4 sec.

D

7 sec.

Soln.
Ans: a

The total distance to be covered is equal to the length of the train. By the time and distance formula, we get time = distance/speed, which gives \$255/51\$ = 5s.

### Question 2

A train of length 656m is running at a speed of 82m/s. How long will it take to cross a pole standing alongside the track?

A

8 sec.

B

9 sec.

C

7 sec.

D

10 sec.

Soln.
Ans: a

The total distance to be covered is equal to the length of the train. By the time and distance formula, we get time = distance/speed, which gives \$656/82\$ = 8s.

### Question 3

Two trains are moving in same direction on two parallel tracks. How many seconds will they take to cross each other if the sum of their lengths is 336m, and the difference of their speeds is 48m/s?

A

7 sec.

B

8 sec.

C

6 sec.

D

9 sec.

Soln.
Ans: a

The total distance is equal to the sum of the lengths of the trains, so s = 336. This distance has to be covered at a net relative speed equal to the difference of the speeds of the two trains, so v = 48. The time will be distance/speed = \$336/48\$ = 7s.

### Question 4

A train of length 190 m crosses a bridge at a speed of 45 km/h in 21 seconds. What is the length of the bridge?

A

3212 meters.

B

3213 meters.

C

3211 meters.

D

3214 meters.

Soln.
Ans: a

In 21 seconds the train covers a distance of 21 × 45 × (18/5) = 3402 meters. This distance is the sum of the lengths of the train and the bridge. Subtracting the length of the train we get the length of the bridge = 3402 - 190 = 3212 meters.

### Question 5

A train speeding at 90 km/h crosses the platform in 60seconds, but it takes 5 seconds to cross a man standing on the same platform. What is the length of the train?

A

1375 meters.

B

1376 meters.

C

1374 meters.

D

1377 meters.

Soln.
Ans: a

The speed of the train in m/s is 90 × (5/18) = 25 m/s. The length of the train can be obtained from the time it takes to cross the man = \$25 × 5\$ = 125meters. The combined length of the train and platform can be obtained from the time it takes to cross the platform, = \$25 × 60 = 1500\$ meters. Subtracting, we get the length of the train = 1375 m.