A train is moving at a speed of 20 m/s and crosses a pole in 8 seconds. How long will it take to cross another train which is running in opposite direction at double speed and half the length of the first train?
Since the speed of the train is 20 m/s and it takes 8 seconds to cross the pole, so the length of the train is 20 × 8 = 160 metres
Now the other train is coming at double speed = 40 m/s and its length is half = 80 metres
So the total length to be crossed becomes = 160 + 80 = 240 meters
And the relative speed becomes 40 + 20 = 60 m/s
Therefore, the time taken = 240/60= 4 seconds
Workspace
Two trains 165 m and 135 m long run at the speed of 70 km/hr and 38 km/hr respectively in opposite directions on parallel tracks. The time (in seconds) which they take to cross each other is:
A train started from point A at a speed of 60 km/hr and after 2 hours another train of same length started from A at a speed of 80 km/hr in the same direction as the first one. After how much time the second train will meet the first train?
Let after x hours the second train will meet the first train.
Because distance is same,
=> S1 t1 = S2 t2
=> 60 (x + 2) = 80 × x
=> 60x + 120 = 80x
=> 80x – 60x = 120
=>20x = 120
=> x = 6 hours
Workspace
How many seconds will a 500 metre long train take to cross a man walking with a speed of 3 km/hr in the direction of the moving train if the speed of the train is 63 km/hr?
Two trains running in opposite directions cross a man standing on the platform in 27 seconds and 17 seconds respectively and they cross each other in 23 seconds. The ratio of their speeds is?
Let the speeds of the two trains be x m/sec and y m/sec respectively.
Then, length of the first train = 27 x meters, and
length of the second train = 17 y meters.
(27 x + 17 y) / (x + y) = 23
=> 27 x + 17 y = 23 x + 23 y
=> 4 x = 6 y
=> x/y = 3/2 = 3 : 2
Workspace
Two stations A and B are 110 kms apart on a straight line. One train starts from A at 7 a.m and travels towards B at 20km per hour speed Another train starts from B at 8 a.m. and travels towards A at a speed of 25 Km per hour at what time will they meet?
Distance covered by B in (x-1) hrs = 25 (x -1) km.
So they meet at 10 a.m.
Workspace
A jogger running at 9 kmph alongside a railway track is 240 meters ahead of the engine of a 120-metre long train running at 45 kmph in the same direction. In how much time will the train pass the jogger?
Speed of train relative to jogger = (45-9) = 36 kmph
===== >>>> 36*(5/18) = 10 m/sec
Distance to cover = 240 + 120 = 360 metres
Time = Distance/Speed
So,
======>>>>> Time = 360/10 = 36 sec
Workspace
Two trains of equal lengths take 10 seconds and 15 seconds respectively to cross a telegraph post. If the length of each train be 120 meters, in what time (in seconds) will they cross each other traveling in opposite direction?
A train overtakes two persons who are walking in the same direction in which the train is going, at the rate of 2 kmph and 4 kmph and passes them completely in 9 and 10 seconds respectively. Find the length of train?
First person speed = 2*(5/18) = 5/9 m/sec
Second person speed = 4*(5/18) = 10/9 m/sec
Let the length of the train is x meter and speed is y m/sec
then,
So length of train is 50 metre
Workspace
A pilot flies an aircraft at a certain speed for a distance of 800 km. He could have saved 40 min by increasing the average speed of the plane by 40 km/h. Find the average speed of the aircraft.
A train 110 metres long is running with a speed of 60 kmph. In what time will it pass a man who is running at 6 kmph in the direction opposite to that in which the train is going?
