Question

A train travelling at 12 m/s accelerates to 20 m/s in 5 seconds.

What will its speed (final velocity) be after another 3 seconds if it continues to accelerate at the same rate correct to 1 decimal place?

Answer 1

The acceleration of a train

$$a=\frac{\Delta v}{\Delta t}=\frac{(20-12)\:\rm m/s}{5\:\rm s}=1.6\:\rm m/s^2$$

The final velocity

$$v_f=v_i+at\\ =20\:\rm m/s+1.6\: m/s^2\times 3\: s=24.8\: m/s$$