In an unfortunate hunting accident, a physics professor is nonfatally shot by by an arrow of mass

0.050 kg. The arrow was fired from a spring-loaded launcher in which a spring, with spring constant k = 80 N/m,
was initially compressed by 0.25 m. The shooter, as yet unidentified, is known to have fired from a window 10 m
above where the professor was hit. The arrow penetrated the professor’s body to a depth of 0.10 m

I don't mind helping to find answers, but I resent having to provide the questions as well.