A van accelerates uniformly down an inclined hill going from reast to `30m//s` in `6s`. During the acceleration , a toy of mass `m=0.1kg` hangs by a light string from the van's ceiling . The acceleration is such that string remains perpendicular to the ceiling. `(` Take `g=10m//s^(2))`

The angle `theta ` of the incline is `:`

Options

A. `30^(@)`
B. `60^(@)`
C. `90^(@)`
D. `45^(@)`

Answer

A

Explanation

Acceleration of the van `=(30)/(6)=5 m//s^(2)`
`g sin theta =a`
`rArr sin theta =(1)/(2)`
`rArr theta=30^(@)`