Explanation:
One approach to the problem is to first calculate the coefficient of static friction = 12 N/(20 kg x 9.8 m/s2) = 0.06. When the surface is inclined at 30 degrees, the normal force of the surface on the object is reduced to cos(30)x 9.8 m/s2 x 20 kg = 170 N. Hence, the transverse force required to initiate sliding is 0.06 x 170 = 10.2 N. This figure is less than the transverse force due to gravitational acceleration = sin 30 x 196 = 98 N. Hence 98+10 = 108 N is required to start the block sliding up the incline.
