A car is moving along a circle with constant speed on an inclined plane as shown in diagram. Then friction force on car will be in horizontal direction at least at one point :

Options

A. in portion 'AB' including point A and B
B. in portion 'BC' including point B and C
C. in portion 'CD' including point C and D
D. in portion 'DA' including point D and A

Answer

B, C

Explanation

Friction force acting on car will be resultant of the components shown in the diagram.
`f_(g)` and `f_(c)` are components of friction force that balance gravitational pull and provides centripetal force respectively.
The resultant of `f_(g)` adn `f_(c)` can be horizontal only for a point at BC adn CD and not for AB and BD.