question_answer

A plumb line is suspended from a ceiling of a car moving with horizontal acceleration of a. What will be the angle of inclination with vertical                                [Orissa JEE 2003]

A)           \[{{\tan }^{-1}}(a/g)\]       

B)             \[{{\tan }^{-1}}(g/a)\]

C)             \[{{\cos }^{-1}}(a/g)\]

D)               \[{{\cos }^{-1}}(g/a)\]

Correct Answer: A

Solution :

                When car moves towards right with acceleration  a then due to pseudo force the plumb line will tilt in backward direction making an angle \[\theta \] with vertical.              From the figure,             \[\tan \theta =a/g\]              \[\therefore \] \[\theta ={{\tan }^{-1}}(a/g)\]