Question

At a turn of track is banked for optimum speed of $40km/h$. At the instant shown in the figure a car is travelling out of the plane of the figure. If the car travels at $60km/h$, the net frictional force acting on the wheels must be :

• A. static in nature and point downward along the bank of the track for safe driving
• B. static in nature and point upward along the bank of the track for safe driving
• C. kinetic in nature and points upward along the bank of the track for safe driving
• D. kinetic in nature and points downwards along the bank of the track for safe driving

Answer 1

The correct option is A static in nature and point downward along the bank of the track for safe driving

Due to centrifugal force acting on the car, the car tends to move away from the center, up the slope.

As friction opposes the motion, friction is in opposite direction of centrifugal force.

Thus friction acts towards the center of curve i.e. downward along the track.

It is of static nature as there is no motion in direction of this friction.

So, option A is correct.