Question

Two radius $A$ and $B$ of length $400m$ are moving on two parallel track with a uniform speed of $72km{h}^{-1}$ in the same direction, with $A$ ahead of $B$. The driver of $B$ decides to overtake $A$ and accelerates by $1s^2$. If after $50s$, the guard of $B$ just brushes path the driver of $A$, what was the original distance between them?

Answer 1

we have,

For train A,

$s=ut+\frac{1}{2}a{t}^2$

$=\frac{72\times 1000}{3600}\times 50+\frac{1}{2}\times 0\times {50}^2$

$=20\times 50=1000m$

For train B,

$s=ut+\frac{1}{2}a{t}^2$

$=\frac{72\times 1000}{3600}\times 50+\frac{1}{2}\times 1\times {50}^2$

$=20\times 50+1250=2250m$

Length of both the trains $=2\times 400=800m$

Hence, the original distance between the driver of train A and the guard train B is

$2250-1000-800=450m$