(c) $Here,\ \ \sin{\theta = \frac{1}{l}}$
Let required acceleration of inclined plane be a for the object to remain stationary relative to incline, we have
[image:5_image191.emf]
$ma\cos{\theta =}mg\sin\theta$
$a = g\tan{\theta = g\frac{1}{\sqrt{l^{2} - 1}}}$