A block is kept on a frictionless inclined surface with angle of inclination `alpha`. The incline is given an acceleration 'a' to keep the block stationary. Then a is equal to

Options

A. `g tan alpha`
B. `g `
C. ` g cosec alpha `
D. `(g)/ ( tan alpha )`

Answer

A

Explanation

The incline is given an acceleration a. Acceleration of the block is to the right. Pseudo acceleration a acts on masina the block to the left. As it is clear from figure, the block will remain stationary, when
`ma cos alpha = mg sin alpha or a = ( g sin alpha)/( cos alpha) = g tan alpha `