It is given that the road is banked for a speed of 40km/hr. If the car continues at this speed, it is possible that it turns without skidding. Hence, (A) is incorrect.

However, if it slows down than this speed, then the forces on the car in inward and outward directions will not cancel out and net force will be inwards. Therefore, it will slip down. (B.) is true.

When the car turns at the exact speed of 40km/hr,

Net force on the car by the road= mv²/r(sinθ)

where θ = angle of banking

⇒ Option (C) is false.

Since, sinθ≤1

⇒ rsinθ ≤ r

⇒ mv²/rsinθ ≥ mv²/r

⇒ Force on car by road ≥ mv²/r

We know that the normal reaction N=mg

And, N cosθ=mv²cosθ/r

⇒ mg=mv²cosθ/r

Also, cosθ≤1

⇒ mv²cosθ ≤ mv²

⇒ mv²cosθ/r ≤ mv²/r

⇒ mg ≤ mv²/r

⇒ mg ≤ mv²/r sinθ

⇒ mg ≤ Force on car by road θ

Therefore, (D.) is true.