Question

You are at a train station, standing next to the train at the front of the first car. The train starts moving with constant acceleration, and 7.0 s later the back of the first car passes you. Part A How long does it take after the train starts moving until the back of the seventh car passes you

Answer 1

18.5 s

Step-by-step explanation:

We are given that

Time,t=7 s

Number of cars=7

Initial velocity =u=0

Length of a car=L

`S=ut+(1)/(2)at^2`

Using the formula

`L=0+(1)/(2)(7)^2a=24.5a`

`a=(L)/(24.5) m/s^2`

Length of seven cars=7L

`7L=0+(1)/(2)((L)/(24.5)t'^2`

`7L=(1)/(2)* (L)/(24.5)t'^2`

`7* 2* 24.5=t'^2`

`t'=√(7* 2* 24.5)=18.5 s`

Hence,it takes 18.5 s after the train starts moving until the back of the seventh car passes you