Question

A train 4.00 3 102 m long is moving on a straight track with a speed of 82.4 km/h. The engineer applies the brakes at a crossing, and later the last car passes the crossing with a speed of 16.4 km/h. Assuming constant acceleration, determine how long the train blocked the crossing. Disregard the width of the crossing.

Answer 1

The value is
`t  =29.2  \  s`

Step-by-step explanation:

From the question we are told that

Generally the average velocity of the train is mathematically represented as

`v  =  (u +  v)/(2)`

substituting 82.4 km/h for u and 16.4 km/h. for v

`v  =  (82.4 + 16.4)/(2)`

`v  =  49.4 \  km/h`

Generally the time taken is mathematically represented as

`t  =  ( L)/(v)`

substituting 49.4 \ km/h for v and
`4.00 * 10^2 \  m  =  0.400 \  km`

`t  =  ( 0.400)/(49.4)`

`t  = 0.00809 \  h`

converting to seconds

`t  = 0.00809 * 3600`

`t  =29.2  \  s`