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 = mgR = mg(v_0^2 sin 2 theta)/g`