Average torque on a projectile of mass 𝑚, initial speed 𝑢 and angles of projection θ, between initial and final position 𝑃 and 𝑄 as shown in figure about the point of projection is

Question: Average torque on a projectile of mass 𝑚, initial speed 𝑢 and angles of projection θ, between initial and final position 𝑃 and 𝑄 as shown in figure about the point of projection is