\begin {corrige}[\thechapter ]{\i }
\begin{enumerate}[label=\fcolorbox{bleu}{bleu}{\color{white}\bfseries\arabic*}]
\item 78 m/s = $78\times 3,6$ km/h = 280,8 km/h.
\item 234 km/h = $234\div 3,6$ m/s = 65 m/s.
\item 18 m$^3$/h = $18\times \np{1000} \ell$/\np{3600} s = 5 $\ell$/s.
\item 9 Wh = 9 W $\times$ 60 min = 0,009 kW $\times$ 60 min = 0,54 kWmin.
\item 0,3 kg/m$^3$ = $0,3\times 1000$ g/\np{1000000} cm$^3$ = \np{0,0003} g/cm$^3$.
\item 450 Wj = 450 W $\times$ 24 h = $450\times 0,001$ kW $\times$ 24 h = 10,8 kWh.
\end{enumerate}
\end {corrige}
