A circular road of radius R is banked for a speed v = 40 km/hr. A car of mass m attempts to go on the circular road, the friction coefficient between the tyre and road is negligible:

Car can make a turn without skidding at 40 km/hr. The car will slip down the slope if it runs at a speed less than 40 km/hr.N sin θ = mv2r   ⇒  N = 1sin θ(mv2r)and N cos θ = mg    ⇒ N = mgcos θ∵  sin θ and cos θ < 1So N > mg and N > mv2r