What was the speed of vehicle C on day 2 in terms of metres per second?

Required speed of vehicle of C

$=\left(\frac{810}{18}\right) \mathrm{kmph}=\left(\frac{810}{18} \times \frac{5}{18}\right) \mathrm{m} / \mathrm{sec}$

$=12.5 \mathrm{~m} / \mathrm{sec} .$