A particle having mass m is projected with a velocity `v_(0)` from a point P on a horizontal ground making an angle `theta` with horizontal. Find out the torque about the point of projection acting on the particle when
It is just about to hit the ground back ?

Explanation

When particle is at point Q then `tau` about point P is `tau_(p) = r_(bot)F`
`r_(bot) = R , F = mg `
`tau _(p) = mg R = "mg"(V_(0)^(2) sin 2 theta)/(g) `