Answer:
[tex]v_{new}=9.9ms^{-1}[/tex]Explanation: Assuming that it took one second to throw the tool away, then we have to use the final velocity formula to get the new velocity:
[tex]v(t)=v_o+at[/tex]One second would imply that the deceleration in the initial astronaut velocity is:
[tex]\begin{gathered} a=-2.4ms^{-2} \\ \end{gathered}[/tex]Note the sign convention!
The new velocity of the astronaut after the throw would be now:
[tex]\begin{gathered} t=1s \\ \therefore\Rightarrow \\ v(1s)=12.3ms^{-1}+(-2.4ms^{-2})(1s)=(12.3-2.4)ms^{-1} \\ v_{new}=9.9ms^{-1} \end{gathered}[/tex]