An ideal gas undergoes a reversible process in which the pressure varies linearly with volume. The conditions at the start (subscript $1$) and at the end (subscript $2$) of the process with usual notation are: $p_1 = 100 \: kPa$, $V_1 = 0.2 \: m^3$ and $p_2=200 \: kPa$, $V_2 = 0.1 \: m^3$ and the gas constant, $R=0.275\:kJ/kg-K$. The magnitude of the work required for the process (in $kJ$) is ________