Respuesta :

v1 - velocity first train
v2 - velocity second train
v2 > v1

v2 - v1 = 17 mph

We know, that: 
[tex]s_1+s_2=210 \ [miles] \\ \\ t_1=t_2=2h[/tex]

So:

[tex]v_1=\dfrac{s_1}{t_1}=\dfrac{s_1}{2} \\ \\ v_2=\dfrac{s_2}{t_2}=\dfrac{s_2}{2} \\ \\ \\ v_1+v_2= \dfrac{s_1}{2}+\dfrac{s_2}{2} \\ \\ v_1+v_2= \dfrac{s_1+s_2}{2} \\ \\ v_1+v_2= \dfrac{210}{2}=105[/tex]

NOw we've got simple system of equations:

[tex]+\begin{cases} v_2-v_1=17 \\ v_2+v_1=105\end{cases} \\ \\ 2v_2=122 \qquad /:2 \\ \\ v_2=61 \qquad [mph] \\ \\ v_2-v_1=17 \\ \\ 61-v_1=17 \\ \\ v_1=44[/tex]

Velocities of these trains are  61mph  and 44mph
Ok, so we know that 2 trains exist; train A and train B.

Let's say that train A travels at a speed n:

A=n

Let's also say that train B travels at a speed n-17:

B=n-17

Now, we both know that both trains will meet each other in 2 hours' time and that they were both once 210 miles apart, so let's form the equation:

2n + 2(n-17) = 210

And from here let's find out what speed n is...

2n + 2n - 34 = 210

4n - 34 = 210

4n = 244

n=244/4

Therefore, n=61.

This means that train A was travelling at 61 mph whilst train B was travelling at (61-17) mph which translates into 44 mph.

So there we have it:

Train A was travelling at 61 mph, which means that over a period of 2 hours it would have travelled a distance of 122 miles.

Train B was travelling at 44 mph, which means that over a period of 2 hours it would have travelled a distance of 88 miles.

{122 miles + 88 miles = 210 miles}

Otras preguntas