Question

A block 'B' is just fitting between two plane inclined at an angle 'q'. The combination of plane is inclined at angle 'a' with horizontal. If coefficient of friction between block and the plane 'm' is insufficient to stop slipping, then acceleration of block is –

• A. g{sin a – m cosa}
• B. $g \left\{ \sin \alpha - \mu \frac { \cos \alpha } { \sin ( \theta / 2 ) } \right\}$
• C. g {sin a – 2 m cosa cosq/2}
• D. g {sin a – m cosa. sin (q/2)}

Answer 1

Answer: (B)

$g \left\{ \sin \alpha - \mu \frac { \cos \alpha } { \sin ( \theta / 2 ) } \right\}$

Answer 2

Sol. Force diagram of block for the view shown

̃ N = $\frac { m g \cos \alpha } { 2 \sin ( \theta / 2 ) }$

\ Net friction up the plane = 2 mN

= mmg $\frac { \cos \alpha } { \sin ( \theta / 2 ) }$

\ a = g $\left\{ \sin \alpha - \mu \frac { \cos \alpha } { \sin ( \theta / 2 ) } \right\}$