a train 100 meters in lenght is running at a speed of about 40km/hr in what time will it pass a telegraph post

The speed of the train

=40 kmph

=(40*1000)/60*60 m/sec

=100/9 m/sec

When a train passes a telegraph post,it passes its own length only

It has to pass a distance of 100 m

Time=distance/speed

=100 divided by 100/9

=100*9/100

=9 seconds

The train must cover a distance of 100m (the length of the train + the length of the post --- treat the post as having a length of 0)

speed = 40km/hr = 40000/3600 m/s = 100/9 m/s

distance = 100m

time = distance / speed

= 100m / (100/9) m/s

= 9 seconds

Since the train is moving at about 40km/hr, it will take about 9 seconds to cross the telegraph post.

If a train was 40km or 40000 meters in length, it would pass a telegraph pole entirely in 1 hour going 40km per hour. A train of 1000meter in length would pass the telegraph pole in 1000/40000 hr or 1/40 hr. A train 100 meters long would take 100/40000 hr or 1/400 hr or 0.0025 hr or 0.0025 (60 min/1 hr)(60 sec/1 min)= 9 sec to pass the telegraph pole.

You are basically asking how long it will take the train to travel 100 meters. (100 m is a very short train)

t =d/v

t = (100 meter/ 40 000m-/hr) x 60 min/hr x 60sec/min = 9 sec

40 km = 40 000 m

60 min = 1hr

60 sec = 1 min

I am not sure where the train would find a telegraph pole these days.

Time=Distance/speed

=0.1/40

Answer=9 seconds

Well, those guys aren't solving the answers. There is no chance to answer the question correctly. Since no distance between two telegraph post was given.

100 / (40000/60/60) = 9 seconds

100 m to pass at 40000/3600 m/sec

It will take an infinite amount of time. There aren't any telegraph posts any more.

0.1/40 = 0.0025 hours = 9 sec

----------

Ideas: Used unit analysis.

(100 m)(1 km/1000 m)(1 hr/40 km)(3600 sec/1hr) = 9 sec

The question is if you are going 11.11m/s how long will it take to travel 100m . ans 9s