# http://www.enotes.com/homework-help/train-100-metres-long-starts-from-rest-station-442022?qadded=1 Using this graph or otherwise, Find the velocity with which and the time at which the front of the...

http://www.enotes.com/homework-help/train-100-metres-long-starts-from-rest-station-442022?qadded=1

Using this graph or otherwise,

Find the velocity with which and the time at which the front of the train passed B

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### 1 Answer

The distance traveled can be obtained from the area of the time-velocity graph. As we know when the train passes the post it will travel 100m in 10s. In the graph this region is a trapezoid and its area will be 100.

Area of trapezoid `= (11+V)/2xx10`

`(11+V)/2xx10 = 100`

`V = 9`

So the velocity of train at the start of post is 9m/s.

Using gradient of the graph we can say;

`V/T = 11/(T+10)`

`9/T = 11/(T+10)`

`T = 45s`

*So the front of train will pass B after 45 seconds it started travel and with a velocity of 9m/s.*

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