A train starts from rest at station A and accelerates at 0.6 m/s^2 for 60 s. Afterwards it travels with a constant velocity for 25 min. It then decelerates at 1.2 m/s^2 until it is brought to rest at station B. Determine the distance between the stations.

Respuesta :

Answer:

The distance between the station A and B will be:

[tex]x_{A-B}=55.620\: km[/tex]  

Explanation:

Let's find the distance that the train traveled during 60 seconds.

[tex]x_{1}=x_{0}+v_{0}t+0.5at^{2}[/tex]

We know that starts from rest (v(0)=0) and the acceleration is 0.6 m/s², so the distance will be:

[tex]x_{1}=\frac{1}{2}(0.6)(60)^{2}[/tex]

[tex]x_{1}=1080\: m[/tex]

Now, we need to find the distance after 25 min at a constant speed. To get it, we need to find the speed at the end of the first distance.

[tex]v_{1}=v_{0}+at[/tex]

[tex]v_{1}=(0.6)(60)=36\: m/s[/tex]

Then the second distance will be:

[tex]x_{2}=v_{1}*1500[/tex]

[tex]x_{2}=(36)(1500)=54000\: m[/tex]        

The final distance is calculated whit the decelerate value:

[tex]v_{f}^{2}=v_{1}^{2}-2ax_{3}[/tex]

The final velocity is zero because it rests at station B. The initial velocity will be v(1).

[tex]0=36^{2}-2(1.2)x_{3}[/tex]

[tex]x_{3}=\frac{36^{2}}{2(1.2)}[/tex]  

[tex]x_{3}=540\: m[/tex]

Therefore, the distance between the station A and B will be:

[tex]x_{A-B}=x_{1}+x_{2}+x_{3}[/tex]  

[tex]x_{A-B}=1080+54000+540=55.620\: km[/tex]  

I hope it helps you!