Answer:
The speed of the man is 0.302m/s in the opposite direction.
Explanation:
We need to apply the theorem of linear momentum:
[tex]m1*vo1+m2*vo2=m1*vf1+m2*vf2[/tex]
The instant before the man throws the book the velocity is zero:
[tex]86.6kg*(0)+2.40kg(0)=86.6kg*vf1+2.40kg*(10.9m/s)\\\\vf1=\frac{-2.40kg*(10.9m/s)}{86.6kg}\\vf1=-0.302m/s[/tex]