Level 1: Same Curve, Twice the Speed: Twice the Grip?
Bank the road so you need no grip.
A curve of radius 40 m is banked so that a car at 72 km/h needs no friction at all (g = 10 m/s²). The banking angle is:
With no friction, the horizontal part of the normal force supplies the centripetal force and its vertical part balances the weight. Convert the speed first: 72 km/h is 20 m/s.
The road must be banked at 45°. Using 72 km/h without converting it to metres per second, or dividing by the wrong quantity, gives one of the other angles.
Every Level 2 starts from a quick question, Level 1, and changes one thing. Seeing what that change does is the skill JEE Main tests. Try it here, free and with no signup, then read the worked answer.
