A body moves on a horizontal circular road of radius r, with a tangential acceleration at. The coefficient of friction between the body and the road surface Is μ. It begins to slip when its speed is v. (i) v^2=μrg (ii) μg=(v^4/r^2)+at) (iii) μ^2g^2=(v^4/r^2+a^2t (iv) The force of friction makes an angle tan^−1(v^2/atr) with the direction of motion at the point of slipping.