Question

A train $200m$ long crosses a bridge $300m$ long. It enters the bridge with a speed of $3m{s}^{-1}$ and leaves it with a speed of $5m{s}^{-1}$. What is the time taken to cross the bridge?

Answer 1

The acceleration is given as,

$a=\frac{v^2-u^2}{2s}$

$=\frac{{\left(5\right)}^2-{\left(3\right)}^2}{2\times 500}$

$=\frac{16}{1000}m/s^2$

The time taken to cross the bridge is given as,

$t=\frac{v-u}{a}$

$=\frac{5-3}{\frac{16}{1000}}$

$=125s$

Thus, the time taken to cross the bridge is $125s$.