Math Is Fun Forum

  Discussion about math, puzzles, games and fun.   Useful symbols: ÷ × ½ √ ∞ ≠ ≤ ≥ ≈ ⇒ ± ∈ Δ θ ∴ ∑ ∫ • π ƒ -¹ ² ³ °

You are not logged in.

#1 2007-01-17 04:23:00

soha
Real Member
Registered: 2006-07-07
Posts: 2,530

A Train...........

Help Needed


A Train 250 M In Length,crosses A Bridge Of Length 350 M In 20 Seconds.find The Speed Of The Train.


"Let us realize that: the privilege to work is a gift, the power to work is a blessing, the love of work is success!" smile smile
- David O. McKay

Offline

#2 2007-01-17 04:42:14

Toast
Real Member
Registered: 2006-10-08
Posts: 1,321

Re: A Train...........

Mathsy's answer is probably correct...

Speed = Distance/Time
          = 350/20
          = 17.5
Train runs at 17.5m/s.

If you want convert into km/h:
(17.5*60*60)m/h
((17.5*60*60)/1000)km/h
=63km/h

I think the length of the train is irrelevant. It depends on whether the train starts on the bridge or not. My answer is based on the assumption that the nose of the train is touching the start of the bridge.

Last edited by Toast (2007-01-17 07:00:13)

Offline

#3 2007-01-17 06:37:23

mathsyperson
Moderator
Registered: 2005-06-22
Posts: 4,900

Re: A Train...........

I think we need to find the time it would take between the nose of the train going onto the bridge and the back of the train coming off.

For that to happen, the train will have needed to move 600m, and so then its speed would be 30m/s. (Or 108km/h)

But it's an ambiguously worded question, so it's difficult to say.


Why did the vector cross the road?
It wanted to be normal.

Offline

#4 2007-01-17 12:23:14

Stanley_Marsh
Member
Registered: 2006-12-13
Posts: 345

Re: A Train...........

average speed v=s/t , s= bridge length+Train length (because it starts at one end of the bridge , when its tail pass over the other end ,we say it has gone through the bridge. so...


Numbers are the essence of the Universe

Offline

Board footer

Powered by FluxBB